WARNING in l2cap_chan_send

Status: upstream: reported C repro on 2024/04/14 00:26
Subsystems: bluetooth
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+b6919040d9958e2fc1ae@syzkaller.appspotmail.com
First crash: 857d, last: 6d11h
✨ AI Patch Versions (3)
Version Stage Reported Report Link Job
3 moderation 2026/08/13 13:58 Discussion 13d65dad-50b4-4275-9c89-8f2b9ce91f77
2 moderation 2026/08/13 12:12 Discussion bb132695-7f6d-4df7-8464-0dd1708b1661
1 moderation 2026/08/08 21:28 Discussion 59121999-1293-40a6-aeeb-713e2d7dc16b
✨ AI Jobs (7)
ID Workflow Result Correct Bug Created Started Finished Revision
13d65dad patch-iteration WARNING in l2cap_chan_send 2026/08/13 13:36 2026/08/13 13:36 2026/08/13 13:58 67796a05
bb132695 patch-iteration WARNING in l2cap_chan_send 2026/08/13 10:50 2026/08/13 10:50 2026/08/13 12:12 67796a05
59121999 patching WARNING in l2cap_chan_send 2026/08/08 19:09 2026/08/08 19:43 2026/08/08 21:28 5d63f80b
01563697 repro-c Reproduced: ✅ WARNING in l2cap_chan_send 2026/08/07 14:12 2026/08/07 14:12 2026/08/07 18:59 e4ef95d6
a1ddaac8 repro-c 💥 WARNING in l2cap_chan_send 2026/08/06 05:12 2026/08/06 05:12 2026/08/06 12:50 cd5b1963
2ae19954 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in l2cap_chan_send 2026/05/21 02:00 2026/05/21 02:00 2026/05/21 02:42 cf874a1c
52b1f0b4 repro 💥 WARNING in l2cap_chan_send 2026/03/10 12:21 2026/03/10 12:21 2026/03/10 12:21 5c03941b
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] [bluetooth?] WARNING in l2cap_chan_send 0 (2) 2026/08/08 16:58
[syzbot] Monthly bluetooth report (Jul 2026) 0 (1) 2026/07/04 04:32
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 WARNING in l2cap_chan_send (2) -1 1 237d 237d 0/3 auto-obsoleted due to no activity on 2026/03/31 03:01
linux-5.15 WARNING in l2cap_chan_send -1 2 92d 190d 0/3 upstream: reported on 2026/02/05 13:43
linux-6.1 WARNING in l2cap_chan_send -1 1 504d 504d 0/3 auto-obsoleted due to no activity on 2025/07/06 18:42
Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/08 08:25 26m nogikh@google.com upstream report log

Sample crash report:
------------[ cut here ]------------
workqueue: cannot queue hci_tx_work on wq hci0
WARNING: kernel/workqueue.c:2306 at __queue_work+0xd4a/0x1090 kernel/workqueue.c:2305, CPU#1: syz-executor109/5985
Modules linked in:
CPU: 1 UID: 0 PID: 5985 Comm: syz-executor109 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__queue_work+0xd66/0x1090 kernel/workqueue.c:2305
Code: 49 81 c7 70 01 00 00 4c 8d 35 86 dd 5b 0e 48 89 f8 48 c1 e8 03 80 3c 18 00 74 05 e8 a4 20 a5 00 49 8b 75 18 4c 89 f7 4c 89 fa <67> 48 0f b9 3a 4c 89 e8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ef e8
RSP: 0018:ffffc900032d7510 EFLAGS: 00010046
RAX: 1ffff11004fd798a RBX: dffffc0000000000 RCX: ffff8880308b1f00
RDX: ffff88807d1c0970 RSI: ffffffff8a85e850 RDI: ffffffff8fe7e260
RBP: 0000000000000000 R08: ffff888027ebcc3f R09: 1ffff11004fd7987
R10: dffffc0000000000 R11: ffffed1004fd7988 R12: 0000000000000008
R13: ffff888027ebcc38 R14: ffffffff8fe7e260 R15: ffff88807d1c0970
FS:  00007fed8a7926c0(0000) GS:ffff888125866000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fed8c796d58 CR3: 00000000739ba000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 queue_work_on+0x106/0x1c0 kernel/workqueue.c:2452
 l2cap_chan_send+0x168a/0x22f0 net/bluetooth/l2cap_core.c:-1
 l2cap_sock_sendmsg+0x33a/0x4d0 net/bluetooth/l2cap_sock.c:1180
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2684
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
 __sys_sendmmsg+0x273/0x4d0 net/socket.c:2827
 __do_sys_sendmmsg net/socket.c:2854 [inline]
 __se_sys_sendmmsg net/socket.c:2851 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2851
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fed8cfcb649
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fed8a791f58 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000000001f2 RCX: 00007fed8cfcb649
RDX: 000000000000000a RSI: 00007fed8a791f80 RDI: 0000000000000006
RBP: 00007fed8a791f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000040 R11: 0000000000000246 R12: 0000000000000006
R13: 0000000000000000 R14: 00007ffed10ed450 R15: 00007ffed10ed538
 </TASK>
----------------
Code disassembly (best guess):
   0:	49 81 c7 70 01 00 00 	add    $0x170,%r15
   7:	4c 8d 35 86 dd 5b 0e 	lea    0xe5bdd86(%rip),%r14        # 0xe5bdd94
   e:	48 89 f8             	mov    %rdi,%rax
  11:	48 c1 e8 03          	shr    $0x3,%rax
  15:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  19:	74 05                	je     0x20
  1b:	e8 a4 20 a5 00       	call   0xa520c4
  20:	49 8b 75 18          	mov    0x18(%r13),%rsi
  24:	4c 89 f7             	mov    %r14,%rdi
  27:	4c 89 fa             	mov    %r15,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	4c 89 e8             	mov    %r13,%rax
  32:	48 c1 e8 03          	shr    $0x3,%rax
  36:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  3a:	74 08                	je     0x44
  3c:	4c 89 ef             	mov    %r13,%rdi
  3f:	e8                   	.byte 0xe8

Crashes (59):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/08 16:57 upstream a7c7074b58d2 e2beed91 .config console log report C ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2025/09/14 07:31 upstream 5cd64d4f9268 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in l2cap_chan_send
2025/02/16 13:59 upstream 496659003dac 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in l2cap_chan_send
2024/11/20 17:47 upstream bf9aa14fc523 4fca1650 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in l2cap_chan_send
2024/10/02 19:52 upstream e32cde8d2bd7 a4c7fd36 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in l2cap_chan_send
2024/07/04 18:23 upstream 795c58e4c7fc dc6bbff0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in l2cap_chan_send
2024/05/13 07:29 upstream ba16c1cf11c9 9026e142 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in l2cap_chan_send
2026/01/25 12:11 upstream 5dbeeb268b63 40acda8a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in l2cap_chan_send
2025/12/04 15:16 upstream cc25df3e2e22 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in l2cap_chan_send
2025/01/15 08:23 upstream c3812b15000c 7315a7cf .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in l2cap_chan_send
2024/08/02 10:38 upstream c0ecd6388360 1e9c4cf3 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in l2cap_chan_send
2024/08/02 08:00 upstream c0ecd6388360 1e9c4cf3 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in l2cap_chan_send
2024/08/02 07:50 upstream c0ecd6388360 1e9c4cf3 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in l2cap_chan_send
2024/07/08 08:00 upstream 256abd8e550c 7ca8bbea .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in l2cap_chan_send
2026/04/14 07:10 upstream 26ff969926a0 1a086e7c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2026/04/05 22:54 upstream 1791c390149f 4440e7c2 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2025/12/26 13:48 upstream ccd1cdca5cd4 d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2025/12/06 10:50 upstream 416f99c3b16f d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2025/06/22 12:32 upstream 739a6c93cc75 d6cdfb8a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2025/02/09 15:35 upstream 9946eaf552b1 ef44b750 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2024/10/03 02:30 upstream f23aa4c0761a a4c7fd36 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2024/09/10 05:43 upstream bc83b4d1f086 784df80e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2024/09/04 14:39 upstream 88fac17500f4 9d47f20a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2024/08/13 15:32 upstream d74da846046a 24d82c00 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2024/07/18 04:03 upstream b1bc554e009e 0f902625 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in l2cap_chan_send
2025/10/13 05:35 net 3abc0e55ea1f ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2025/09/29 16:56 net 012ea489aeda 86341da6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2025/09/13 09:57 net 201825fb4278 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2025/08/21 07:19 net f7b0b97c2d38 0b9605c8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/09/28 10:09 net d505d3593b52 440b26ec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/09/28 04:18 net d505d3593b52 440b26ec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/09/23 22:51 net c8770db2d544 89298aad .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/09/13 03:18 net 3e705251d998 73e8a465 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/07/20 01:24 net d7e78951a8b8 b88348e9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/07/01 08:32 net 134061163ee5 757f06b1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/06/07 06:07 net d30d0e49da71 121701b6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/06/06 01:42 net f8f0de9d58d9 121701b6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/05/31 19:35 net 13c7c941e729 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/05/15 01:59 net aea27a92a41d fdb4c10c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/05/09 05:57 net 02754103e1f7 20bf80e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2024/04/10 00:20 net f99c5f563c17 56086b24 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in l2cap_chan_send
2026/06/23 14:53 net-next b85966adbf5d 4b1d8f01 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2025/04/21 03:39 net-next 8066e388be48 2a20f901 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2025/03/21 21:55 net-next d9917c7d533c 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/10/26 18:02 net-next 6d858708d465 65e8686b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/09/20 03:49 net-next 9410645520e9 6f888b75 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/07/19 09:39 net-next 51835949dda3 ee4e11c8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/07/16 22:14 net-next 77ae5e5b0072 215bec2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/07/16 22:04 net-next 77ae5e5b0072 215bec2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/07/13 16:14 net-next 69cf87304dcb eaeb5c15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/06/29 00:02 net-next 748e3bbf4721 757f06b1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/06/22 17:25 net-next 185d72112b95 edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/05/19 22:15 net-next 4b377b4868ef c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/05/19 16:02 net-next 4b377b4868ef c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/05/15 02:50 net-next 654de42f3fc6 fdb4c10c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2024/05/06 07:19 net-next cdc74c9d06e7 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in l2cap_chan_send
2026/03/27 16:48 linux-next 66ba480978ce 74a13a23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in l2cap_chan_send
2025/10/16 20:52 linux-next 2433b8476165 19568248 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in l2cap_chan_send
2024/06/17 00:14 linux-next a957267fa7e9 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in l2cap_chan_send
* Struck through repros no longer work on HEAD.