=============================
WARNING: suspicious RCU usage
6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1350 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.0.1899/13184:
 #0: ffffffff90124b68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff90124b68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #0: ffffffff90124b68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x600/0x2000 net/core/rtnetlink.c:4064
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline]
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:39 [inline]
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: do_setlink.constprop.0+0x2ec/0x44b0 net/core/rtnetlink.c:3051
 #2: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x3a/0x2d0 net/ipv6/ip6_fib.c:2263
 #3: ffff8880559c9c30 (&tb->tb6_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff8880559c9c30 (&tb->tb6_lock){+.-.}-{3:3}, at: __fib6_clean_all+0xeb/0x2d0 net/ipv6/ip6_fib.c:2267

stack backtrace:
CPU: 1 UID: 0 PID: 13184 Comm: syz.0.1899 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x166/0x260 kernel/locking/lockdep.c:6865
 __fib6_update_sernum_upto_root+0x221/0x270 net/ipv6/ip6_fib.c:1350
 fib6_ifup+0x19b/0x2a0 net/ipv6/route.c:4818
 fib6_clean_node+0x2a4/0x5b0 net/ipv6/ip6_fib.c:2199
 fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2124
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2172
 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:2252
 __fib6_clean_all+0x107/0x2d0 net/ipv6/ip6_fib.c:2268
 rt6_sync_up+0xc9/0x170 net/ipv6/route.c:4837
 addrconf_notify+0x1709/0x19e0 net/ipv6/addrconf.c:3729
 notifier_call_chain+0xb9/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2176
 __dev_notify_flags+0x2a8/0x2e0 net/core/dev.c:9419
 netif_change_flags+0x108/0x160 net/core/dev.c:9434
 do_setlink.constprop.0+0xddf/0x44b0 net/core/rtnetlink.c:3152
 rtnl_group_changelink net/core/rtnetlink.c:3783 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3937 [inline]
 rtnl_newlink+0x18e0/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95b/0xe90 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x16a/0x440 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmsg+0x16d/0x220 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe69838e969
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:00007fe6991ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe6985b5fa0 RCX: 00007fe69838e969
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 0000000000000003
RBP: 00007fe698410ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe6985b5fa0 R15: 00007ffe4bb3b228
 </TASK>

=============================
WARNING: suspicious RCU usage
6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1357 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.0.1899/13184:
 #0: ffffffff90124b68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff90124b68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #0: ffffffff90124b68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x600/0x2000 net/core/rtnetlink.c:4064
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline]
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:39 [inline]
 #1: ffff8880579bad30 (&dev_instance_lock_key#3){+.+.}-{4:4}, at: do_setlink.constprop.0+0x2ec/0x44b0 net/core/rtnetlink.c:3051
 #2: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0x3a/0x2d0 net/ipv6/ip6_fib.c:2263
 #3: ffff8880559c9c30 (&tb->tb6_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #3: ffff8880559c9c30 (&tb->tb6_lock){+.-.}-{3:3}, at: __fib6_clean_all+0xeb/0x2d0 net/ipv6/ip6_fib.c:2267

stack backtrace:
CPU: 1 UID: 0 PID: 13184 Comm: syz.0.1899 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x166/0x260 kernel/locking/lockdep.c:6865
 __fib6_update_sernum_upto_root+0x16b/0x270 net/ipv6/ip6_fib.c:1357
 fib6_ifup+0x19b/0x2a0 net/ipv6/route.c:4818
 fib6_clean_node+0x2a4/0x5b0 net/ipv6/ip6_fib.c:2199
 fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2124
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2172
 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:2252
 __fib6_clean_all+0x107/0x2d0 net/ipv6/ip6_fib.c:2268
 rt6_sync_up+0xc9/0x170 net/ipv6/route.c:4837
 addrconf_notify+0x1709/0x19e0 net/ipv6/addrconf.c:3729
 notifier_call_chain+0xb9/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2176
 __dev_notify_flags+0x2a8/0x2e0 net/core/dev.c:9419
 netif_change_flags+0x108/0x160 net/core/dev.c:9434
 do_setlink.constprop.0+0xddf/0x44b0 net/core/rtnetlink.c:3152
 rtnl_group_changelink net/core/rtnetlink.c:3783 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3937 [inline]
 rtnl_newlink+0x18e0/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95b/0xe90 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x16a/0x440 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmsg+0x16d/0x220 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe69838e969
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:00007fe6991ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe6985b5fa0 RCX: 00007fe69838e969
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 0000000000000003
RBP: 00007fe698410ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe6985b5fa0 R15: 00007ffe4bb3b228
 </TASK>
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
bridge_slave_1: left allmulticast mode
bridge_slave_1: left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bond0: (slave bond_slave_0): Releasing backup interface
==================================================================
BUG: KASAN: global-out-of-bounds in fib6_ifup+0x257/0x2a0 net/ipv6/route.c:4815
Read of size 8 at addr ffffffff9af9a530 by task syz.0.1899/13184

CPU: 0 UID: 0 PID: 13184 Comm: syz.0.1899 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 fib6_ifup+0x257/0x2a0 net/ipv6/route.c:4815
 fib6_clean_node+0x2a4/0x5b0 net/ipv6/ip6_fib.c:2199
 fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2124
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2172
 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:2252
 __fib6_clean_all+0x107/0x2d0 net/ipv6/ip6_fib.c:2268
 rt6_sync_up+0xc9/0x170 net/ipv6/route.c:4837
 addrconf_notify+0x1709/0x19e0 net/ipv6/addrconf.c:3729
 notifier_call_chain+0xb9/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2176
 netif_state_change+0x165/0x3b0 net/core/dev.c:1530
 do_setlink.constprop.0+0x3632/0x44b0 net/core/rtnetlink.c:3399
 rtnl_group_changelink net/core/rtnetlink.c:3783 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3937 [inline]
 rtnl_newlink+0x18e0/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95b/0xe90 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x16a/0x440 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmsg+0x16d/0x220 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe69838e969
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:00007fe6991ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe6985b5fa0 RCX: 00007fe69838e969
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 0000000000000003
RBP: 00007fe698410ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe6985b5fa0 R15: 00007ffe4bb3b228
 </TASK>

The buggy address belongs to the variable:
 __key.0+0x30/0x40

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1af9a
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea00006be688 ffffea00006be688 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffffffff9af9a400: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
 ffffffff9af9a480: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
>ffffffff9af9a500: 00 00 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
                                     ^
 ffffffff9af9a580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f9
 ffffffff9af9a600: f9 f9 f9 f9 00 00 f9 f9 f9 f9 f9 f9 00 00 f9 f9
==================================================================