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WARNING: suspicious RCU usage in fib6_del (3)

Status: closed as dup on 2025/05/02 01:02
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+2d1f030088fa84f9d163@syzkaller.appspotmail.com
First crash: 48d, last: 11d
▶ ▼ Duplicate of
Title Repro Cause bisect Fix bisect Count Last Reported
WARNING: suspicious RCU usage in __fib6_update_sernum_upto_root net 10 11d 47d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] WARNING: suspicious RCU usage in fib6_del (3) 1 (2) 2025/05/02 01:01
▶ ▼ Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 WARNING: suspicious RCU usage in fib6_del C 35 2028d 2260d 0/1 public: reported C repro on 2019/04/11 00:00
upstream WARNING: suspicious RCU usage in fib6_del net 1 2060d 2060d 0/28 closed as invalid on 2019/11/19 23:24
upstream WARNING: suspicious RCU usage in fib6_del (2) net 1 1744d 1744d 15/28 fixed on 2020/10/10 01:52

Sample crash report:
bridge0: trying to set multicast startup query interval below minimum, setting to 100 (1000ms)
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:2077 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_del+0x1516/0x1550 net/ipv6/ip6_fib.c:2076
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:2089 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_del+0x595/0x1550 net/ipv6/ip6_fib.c:2088
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1975 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_del_route net/ipv6/ip6_fib.c:1974 [inline]
 fib6_del+0x651/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1984 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_del_route net/ipv6/ip6_fib.c:1983 [inline]
 fib6_del+0x67a/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:2029 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
5 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320
 #4: ffff88805d814eb8 (&net->ipv6.fib6_walker_lock){++..}-{3:3}, at: fib6_del_route net/ipv6/ip6_fib.c:2024 [inline]
 #4: ffff88805d814eb8 (&net->ipv6.fib6_walker_lock){++..}-{3:3}, at: fib6_del+0xb3f/0x1550 net/ipv6/ip6_fib.c:2093

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_del_route net/ipv6/ip6_fib.c:2028 [inline]
 fib6_del+0xd5c/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1859 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xdad/0x11c0 net/ipv6/ip6_fib.c:1858
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1861 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xdd6/0x11c0 net/ipv6/ip6_fib.c:1860
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1863 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: 
ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: 
ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: 
ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xdff/0x11c0 net/ipv6/ip6_fib.c:1862
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1865 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xe28/0x11c0 net/ipv6/ip6_fib.c:1864
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1867 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xe51/0x11c0 net/ipv6/ip6_fib.c:1866
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1869 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xe7a/0x11c0 net/ipv6/ip6_fib.c:1868
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1871 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_repair_tree+0xea3/0x11c0 net/ipv6/ip6_fib.c:1870
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1820 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_find_prefix+0x1e8/0x3f0 net/ipv6/ip6_fib.c:1819
 fib6_repair_tree+0x10bd/0x11c0 net/ipv6/ip6_fib.c:1898
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9526
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3141
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb991f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb992dca038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb9921b5fa0 RCX: 00007fb991f8e929
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fb992010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9921b5fa0 R15: 00007fb9922dfa28
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-syzkaller-12058-g64980441d269 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1822 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz.1.3546/18466:
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8fa2e758 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f50f5c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4054
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e13f060 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x9b/0x380 net/ipv6/ip6_fib.c:2316
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff88805cd45830 (&tb->tb6_lock){+...}-{3:3}, at: __fib6_clean_all+0x1ce/0x380 net/ipv6/ip6_fib.c:2320

stack backtrace:
CPU: 0 UID: 0 PID: 18466 Comm: syz.1.3546 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 fib6_find_prefix+0x211/0x3f0 net/ipv6/ip6_fib.c:1821
 fib6_repair_tree+0x10bd/0x11c0 net/ipv6/ip6_fib.c:1898
 fib6_del_route net/ipv6/ip6_fib.c:2045 [inline]
 fib6_del+0xed2/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x67b/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/05 11:42 upstream 64980441d269 6b6b5f21 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: suspicious RCU usage in fib6_del
2025/05/24 23:53 upstream b1427432d3b6 ed351ea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING: suspicious RCU usage in fib6_del
2025/05/24 15:55 upstream 4856ebd99715 ed351ea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: suspicious RCU usage in fib6_del
2025/05/09 01:59 upstream d76bb1ebb558 dbf35fa1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: suspicious RCU usage in fib6_del
2025/05/04 06:31 upstream 2a239ffbebb5 b0714e37 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING: suspicious RCU usage in fib6_del
2025/05/11 02:46 upstream 345030986df8 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING: suspicious RCU usage in fib6_del
2025/06/06 12:19 upstream e271ed52b344 3d899f2c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: suspicious RCU usage in fib6_del
2025/05/25 08:42 upstream d0c22de9995b ed351ea7 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: suspicious RCU usage in fib6_del
2025/05/16 02:32 upstream 088d13246a46 cfde8269 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: suspicious RCU usage in fib6_del
2025/05/01 02:40 upstream 7a13c14ee59d ce7952f4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: suspicious RCU usage in fib6_del
2025/06/03 22:18 upstream 546b1c9e93c2 a30356b7 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: suspicious RCU usage in fib6_del
2025/05/31 21:17 upstream 0f70f5b08a47 3d2f584d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: suspicious RCU usage in fib6_del
2025/06/03 05:28 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci d7fa1af5b33e b396b4bf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING: suspicious RCU usage in fib6_del
2025/05/30 06:58 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci d7fa1af5b33e 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING: suspicious RCU usage in fib6_del
* Struck through repros no longer work on HEAD.