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KASAN: global-out-of-bounds Read in fib6_add_rt2node

Status: closed as invalid on 2025/07/02 15:51
Subsystems: net
[Documentation on labels]
First crash: 89d, last: 85d

Sample crash report:
mac80211_hwsim hwsim54 wlan0: entered promiscuous mode
macvlan2: entered allmulticast mode
mac80211_hwsim hwsim54 wlan0: entered allmulticast mode
==================================================================
BUG: KASAN: global-out-of-bounds in fib6_add_rt2node+0x62f/0x33a0 net/ipv6/ip6_fib.c:1115
Read of size 8 at addr ffffffff99f84588 by task syz.0.6301/29986

CPU: 1 UID: 0 PID: 29986 Comm: syz.0.6301 Not tainted 6.15.0-syzkaller-11061-g7f9039c524a3 #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
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 fib6_add_rt2node+0x62f/0x33a0 net/ipv6/ip6_fib.c:1115
 fib6_add+0x8da/0x18a0 net/ipv6/ip6_fib.c:1535
 __ip6_ins_rt net/ipv6/route.c:1351 [inline]
 ip6_route_add+0xbd/0x190 net/ipv6/route.c:3897
 addrconf_prefix_route net/ipv6/addrconf.c:2487 [inline]
 addrconf_add_linklocal+0x45f/0x6c0 net/ipv6/addrconf.c:3312
 addrconf_addr_gen+0x490/0x580 net/ipv6/addrconf.c:3441
 addrconf_init_auto_addrs+0x711/0xb50 net/ipv6/addrconf.c:-1
 addrconf_notify+0xacc/0x1010 net/ipv6/addrconf.c:3744
 notifier_call_chain+0x1b6/0x3e0 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
 rtnl_configure_link net/core/rtnetlink.c:3589 [inline]
 rtnl_newlink_create+0x61c/0xb00 net/core/rtnetlink.c:3833
 __rtnl_newlink net/core/rtnetlink.c:3940 [inline]
 rtnl_newlink+0x16d6/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cf/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+0x219/0x270 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: 0033:0x7fd50018e969
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:00007fd5010db038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd5003b5fa0 RCX: 00007fd50018e969
RDX: 0000000004040040 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fd500210ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd5003b5fa0 R15: 00007fd5004dfa28
 </TASK>

The buggy address belongs to the variable:
 binder_devices+0x8/0x20

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x19f84
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea000067e108 ffffea000067e108 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:
 ffffffff99f84480: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
 ffffffff99f84500: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
>ffffffff99f84580: 00 f9 f9 f9 00 00 f9 f9 00 00 00 00 00 00 00 00
                      ^
 ffffffff99f84600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff99f84680: 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 00 f9 f9 f9
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/03 05:57 upstream 7f9039c524a3 b396b4bf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce KASAN: global-out-of-bounds Read in fib6_add_rt2node
2025/05/31 10:47 upstream 8477ab143069 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: global-out-of-bounds Read in fib6_add_rt2node
2025/05/30 02:50 upstream 9d230d500b0e 3d2f584d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: global-out-of-bounds Read in fib6_add_rt2node
* Struck through repros no longer work on HEAD.