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
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 BUG: unable to handle kernel paging request in br_del_frame origin:lts-only 8 syz 4 1d14h 22d 0/3 upstream: reported syz repro on 2026/08/12 17:14
upstream general protection fault in br_del_frame prio:normal bridge 8 syz 325 58m 9h12m 0/29 upstream: reported syz repro on 2026/09/04 00:40

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

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/28 23:37 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in br_del_frame
2026/08/27 16:17 linux-6.6.y 93e0c9521fa8 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in br_del_frame
2026/08/25 05:28 linux-6.6.y dc6160265ffc 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in br_del_frame
* Struck through repros no longer work on HEAD.