syzbot
general protection fault in br_del_frame
Status:
upstream: reported on 2026/08/25 05:29
Reported-by: syzbot+50bea8aafbd998152d09@syzkaller.appspotmail.com
First crash: 55d, last: 11d
Sample crash report:
bridge_slave_1: left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]
CPU: 0 PID: 9440 Comm: kworker/u4:20 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: netns cleanup_net
RIP: 0010:__hlist_del include/linux/list.h:987 [inline]
RIP: 0010:hlist_del_rcu include/linux/rculist.h:542 [inline]
RIP: 0010:br_del_frame+0xd1/0x150 net/bridge/br_input.c:463
Code: f8 4c 8b 73 10 48 83 c3 18 49 89 dd 49 c1 ed 03 43 80 7c 25 00 00 74 08 48 89 df e8 69 6d 74 f8 4c 8b 3b 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 f0 6d 74 f8 4d 89 37 4d 85 f6 74
RSP: 0018:ffffc900031f7870 EFLAGS: 00010a06
RAX: 1bd5a00000000024 RBX: ffffffff8f6e4080 RCX: ffff88807aa43c00
RDX: 0000000000000000 RSI: ffffffff8f6e4068 RDI: ffffffff8f6e4078
RBP: 000000000000001d R08: ffffffff91ff150f R09: 1ffffffff23fe2a1
R10: dffffc0000000000 R11: fffffbfff23fe2a2 R12: dffffc0000000000
R13: 1ffffffff1edc810 R14: 0000000000000000 R15: dead000000000122
FS: 0000000000000000(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd8cd427dac CR3: 0000000054f53000 CR4: 00000000003506f0
Call Trace:
<TASK>
br_cfm_port_del+0x116/0x1b0 net/bridge/br_cfm.c:872
del_nbp+0x167/0x9e0 net/bridge/br_if.c:347
br_dev_delete+0x6e/0x130 net/bridge/br_if.c:386
default_device_exit_batch+0x8c0/0xa00 net/core/dev.c:11797
ops_exit_list net/core/net_namespace.c:178 [inline]
cleanup_net+0x785/0xb00 net/core/net_namespace.c:656
process_one_work kernel/workqueue.c:2657 [inline]
process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hlist_del include/linux/list.h:987 [inline]
RIP: 0010:hlist_del_rcu include/linux/rculist.h:542 [inline]
RIP: 0010:br_del_frame+0xd1/0x150 net/bridge/br_input.c:463
Code: f8 4c 8b 73 10 48 83 c3 18 49 89 dd 49 c1 ed 03 43 80 7c 25 00 00 74 08 48 89 df e8 69 6d 74 f8 4c 8b 3b 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 f0 6d 74 f8 4d 89 37 4d 85 f6 74
RSP: 0018:ffffc900031f7870 EFLAGS: 00010a06
RAX: 1bd5a00000000024 RBX: ffffffff8f6e4080 RCX: ffff88807aa43c00
RDX: 0000000000000000 RSI: ffffffff8f6e4068 RDI: ffffffff8f6e4078
RBP: 000000000000001d R08: ffffffff91ff150f R09: 1ffffffff23fe2a1
R10: dffffc0000000000 R11: fffffbfff23fe2a2 R12: dffffc0000000000
R13: 1ffffffff1edc810 R14: 0000000000000000 R15: dead000000000122
FS: 0000000000000000(0000) GS:ffff8880b8d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ef859d5000 CR3: 00000000320b4000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
0: f8 clc
1: 4c 8b 73 10 mov 0x10(%rbx),%r14
5: 48 83 c3 18 add $0x18,%rbx
9: 49 89 dd mov %rbx,%r13
c: 49 c1 ed 03 shr $0x3,%r13
10: 43 80 7c 25 00 00 cmpb $0x0,0x0(%r13,%r12,1)
16: 74 08 je 0x20
18: 48 89 df mov %rbx,%rdi
1b: e8 69 6d 74 f8 call 0xf8746d89
20: 4c 8b 3b mov (%rbx),%r15
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 ff mov %r15,%rdi
34: e8 f0 6d 74 f8 call 0xf8746e29
39: 4d 89 37 mov %r14,(%r15)
3c: 4d 85 f6 test %r14,%r14
3f: 74 .byte 0x74
Struck through repros no longer work on HEAD.