kernel BUG in fib6_add_rt2node (2)

Status: fixed on 2026/05/06 16:40
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+cb809def1baaac68ab92@syzkaller.appspotmail.com
Fix commit: bbf4a17ad9ff ipv6: Fix ECMP sibling count mismatch when clearing RTF_ADDRCONF
First crash: 227d, last: 181d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH net] ipv6: Fix ECMP sibling count mismatch when clearing RTF_ADDRCONF 3 (3) 2026/02/05 16:50
[syzbot] [net?] kernel BUG in fib6_add_rt2node (2) 1 (3) 2026/02/04 08:12
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in fib6_add_rt2node net -1 4 354d 400d 0/29 closed as invalid on 2025/09/01 08:35
▶ ▼ Last patch testing requests (9)
Created Duration User Patch Repo Result
2026/02/04 08:12 36m syoshida@redhat.com patch bpf OK log
2026/01/26 15:50 56m retest repro bpf-next OK log
2026/01/26 15:50 57m retest repro bpf-next report log
2026/01/26 15:50 1h01m retest repro bpf-next report log
2026/01/26 15:50 37m retest repro bpf-next report log
2026/01/26 15:50 18m retest repro bpf-next report log
2026/01/12 08:51 50m retest repro bpf error
2026/01/12 08:51 42m retest repro bpf report log
2026/01/12 08:51 43m retest repro bpf report log

Sample crash report:
------------[ cut here ]------------
kernel BUG at net/ipv6/ip6_fib.c:1217!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6010 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:fib6_add_rt2node+0x3433/0x3470 net/ipv6/ip6_fib.c:1217
Code: ff ff 48 8b 4c 24 08 80 e1 07 80 c1 03 38 c1 0f 8c a4 f9 ff ff 48 8b 7c 24 08 e8 08 4d 28 f8 e9 95 f9 ff ff e8 0e 64 c2 f7 90 <0f> 0b 44 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 7a fa ff ff 4c 89 ff
RSP: 0018:ffffc900030a7660 EFLAGS: 00010293
RAX: ffffffff89fee772 RBX: 0000000000000001 RCX: ffff88807a2abd00
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: ffffc900030a7850 R08: ffffc900030a7910 R09: 0000000000000050
R10: 0000000000000000 R11: fffff52000614f24 R12: ffff888074779818
R13: ffff888074779800 R14: dffffc0000000000 R15: 0000000000000002
FS:  000055556dfd5500(0000) GS:ffff8881260b1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000074636000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 fib6_add+0x8da/0x18a0 net/ipv6/ip6_fib.c:1532
 __ip6_ins_rt net/ipv6/route.c:1351 [inline]
 ip6_route_add+0xde/0x1b0 net/ipv6/route.c:3946
 ipv6_route_ioctl+0x35c/0x480 net/ipv6/route.c:4571
 inet6_ioctl+0x219/0x280 net/ipv6/af_inet6.c:577
 sock_do_ioctl+0xdc/0x300 net/socket.c:1245
 sock_ioctl+0x576/0x790 net/socket.c:1366
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf1918f749
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:00007ffe117d8c08 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fbf193e5fa0 RCX: 00007fbf1918f749
RDX: 0000200000000000 RSI: 000000000000890b RDI: 0000000000000007
RBP: 00007fbf19213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf193e5fa0 R14: 00007fbf193e5fa0 R15: 0000000000000003
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fib6_add_rt2node+0x3433/0x3470 net/ipv6/ip6_fib.c:1217
Code: ff ff 48 8b 4c 24 08 80 e1 07 80 c1 03 38 c1 0f 8c a4 f9 ff ff 48 8b 7c 24 08 e8 08 4d 28 f8 e9 95 f9 ff ff e8 0e 64 c2 f7 90 <0f> 0b 44 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 7a fa ff ff 4c 89 ff
RSP: 0018:ffffc900030a7660 EFLAGS: 00010293
RAX: ffffffff89fee772 RBX: 0000000000000001 RCX: ffff88807a2abd00
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: ffffc900030a7850 R08: ffffc900030a7910 R09: 0000000000000050
R10: 0000000000000000 R11: fffff52000614f24 R12: ffff888074779818
R13: ffff888074779800 R14: dffffc0000000000 R15: 0000000000000002
FS:  000055556dfd5500(0000) GS:ffff8881260b1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000074636000 CR4: 00000000003526f0

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/11 17:42 bpf 1d528e794f3d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/11 14:24 bpf-next 759377dab35e d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/13 20:37 bpf 1d528e794f3d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/12 22:27 bpf 1d528e794f3d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/14 01:00 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/13 19:27 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/13 10:50 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/13 03:51 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/12 19:45 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/12 13:47 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/29 08:23 bpf-next f14cdb1367b9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/28 00:21 bpf-next f14cdb1367b9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/26 20:23 bpf-next f14cdb1367b9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/22 02:03 bpf-next d2749ae85aec d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/14 03:10 bpf-next 759377dab35e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/13 15:38 bpf-next 759377dab35e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/11 16:36 bpf-next 759377dab35e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
2025/12/11 09:33 bpf-next 759377dab35e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce kernel BUG in fib6_add_rt2node
* Struck through repros no longer work on HEAD.