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: 10d, last: 6d10h
Sample crash report:
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: 26067 Comm: syz.2.5403 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__hlist_del include/linux/list.h:980 [inline]
RIP: 0010:hlist_del_rcu include/linux/rculist.h:513 [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 d9 be 76 f8 4c 8b 3b 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 60 bf 76 f8 4d 89 37 4d 85 f6 74
RSP: 0018:ffffc90003c16f30 EFLAGS: 00010a06
RAX: 1bd5a00000000024 RBX: ffffffff8e8e6c80 RCX: 0000000000080000
RDX: ffffc9000d12b000 RSI: 000000000001f954 RDI: ffffffff8e8e6c78
RBP: 000000000000001d R08: ffffffff911ef50f R09: 1ffffffff223dea1
R10: dffffc0000000000 R11: fffffbfff223dea2 R12: dffffc0000000000
R13: 1ffffffff1d1cd90 R14: 0000000000000000 R15: dead000000000122
FS: 00007ff7d2f4b6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2ee2b7e940 CR3: 00000000644af000 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
rtnl_delete_link net/core/rtnetlink.c:3270 [inline]
rtnl_dellink+0x4ed/0x7c0 net/core/rtnetlink.c:3323
rtnetlink_rcv_msg+0x843/0xf90 net/core/rtnetlink.c:6484
netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_write_iter+0x2dc/0x420 net/socket.c:1161
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x474/0x9a0 fs/read_write.c:584
ksys_write+0x151/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff7d1f9e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff7d2f4b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ff7d2225fa0 RCX: 00007ff7d1f9e159
RDX: 0000000000000024 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007ff7d2035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff7d2226038 R14: 00007ff7d2225fa0 R15: 00007ffc86790478
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hlist_del include/linux/list.h:980 [inline]
RIP: 0010:hlist_del_rcu include/linux/rculist.h:513 [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 d9 be 76 f8 4c 8b 3b 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 60 bf 76 f8 4d 89 37 4d 85 f6 74
RSP: 0018:ffffc90003c16f30 EFLAGS: 00010a06
RAX: 1bd5a00000000024 RBX: ffffffff8e8e6c80 RCX: 0000000000080000
RDX: ffffc9000d12b000 RSI: 000000000001f954 RDI: ffffffff8e8e6c78
RBP: 000000000000001d R08: ffffffff911ef50f R09: 1ffffffff223dea1
R10: dffffc0000000000 R11: fffffbfff223dea2 R12: dffffc0000000000
R13: 1ffffffff1d1cd90 R14: 0000000000000000 R15: dead000000000122
FS: 00007ff7d2f4b6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7310a8d286 CR3: 00000000644af000 CR4: 00000000003506f0
----------------
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 d9 be 76 f8 call 0xf876bef9
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 60 bf 76 f8 call 0xf876bf99
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.