WARNING in hci_send_cmd (4)

Status: upstream: reported on 2026/04/25 23:07
Subsystems: bluetooth
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+00f5a866124dc44cce14@syzkaller.appspotmail.com
First crash: 105d, last: 14d
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
b0d75278 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ✅ VMHostTrigger: ❌ WARNING in hci_send_cmd (4) 2026/05/31 08:48 2026/05/31 08:48 2026/05/31 09:46 6b4a8443

			
		
7595eab6 assessment-security 💥 WARNING in hci_send_cmd (4) 2026/05/14 15:06 2026/05/14 15:06 2026/05/14 15:08 6ccb967e
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/e1ee59fddb5fdcd4eb...
truncated to first 200 bytes; open job for full error
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly bluetooth report (Jul 2026) 0 (1) 2026/07/04 04:32
[syzbot] [bluetooth?] WARNING in hci_send_cmd (4) 1 (2) 2026/04/26 19:11
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in hci_send_cmd (3) bluetooth -1 1 236d 232d 0/29 auto-obsoleted due to no activity on 2026/02/09 11:54
linux-6.1 WARNING in hci_send_cmd -1 2 376d 399d 0/3 auto-obsoleted due to no activity on 2025/11/01 12:27
upstream WARNING in hci_send_cmd bluetooth -1 8 656d 904d 0/29 auto-obsoleted due to no activity on 2025/01/25 05:20
upstream WARNING in hci_send_cmd (2) bluetooth -1 2 463d 524d 0/29 auto-obsoleted due to no activity on 2025/08/06 09:07

Sample crash report:
------------[ cut here ]------------
workqueue: cannot queue hci_cmd_work on wq hci0
WARNING: kernel/workqueue.c:2306 at __queue_work+0xd4a/0x10a0 kernel/workqueue.c:2305, CPU#1: syz.9.5538/24051
Modules linked in:
CPU: 1 UID: 0 PID: 24051 Comm: syz.9.5538 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__queue_work+0xd66/0x10a0 kernel/workqueue.c:2305
Code: 49 81 c7 70 01 00 00 4c 8d 35 16 ea a8 0e 48 89 f8 48 c1 e8 03 80 3c 18 00 74 05 e8 d4 ac a6 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:ffffc90003c87778 EFLAGS: 00010046
RAX: 1ffff11007b1d181 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffff888025281970 RSI: ffffffff8aa6aeb0 RDI: ffffffff90362390
RBP: 0000000000000000 R08: ffff88803d8e8bf7 R09: 1ffff11007b1d17e
R10: dffffc0000000000 R11: ffffed1007b1d17f R12: 0000000000000008
R13: ffff88803d8e8bf0 R14: ffffffff90362390 R15: ffff888025281970
FS:  00007fa6345c26c0(0000) GS:ffff888125320000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff01613278 CR3: 0000000054e43000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 queue_work_on+0x106/0x1d0 kernel/workqueue.c:2452
 queue_work include/linux/workqueue.h:699 [inline]
 hci_send_cmd+0xb7/0x1a0 net/bluetooth/hci_core.c:3073
 set_link_security+0x5b1/0x770 net/bluetooth/mgmt.c:1931
 hci_mgmt_cmd+0xa2c/0xfc0 net/bluetooth/hci_sock.c:1719
 hci_sock_sendmsg+0x6e1/0xf50 net/bluetooth/hci_sock.c:1839
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 sock_write_iter+0x2de/0x3e0 net/socket.c:1241
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa63379ce59
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:00007fa6345c2028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa633a15fa0 RCX: 00007fa63379ce59
RDX: 0000000000000007 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007fa633832e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa633a16038 R14: 00007fa633a15fa0 R15: 00007ffd13288fc8
 </TASK>
----------------
Code disassembly (best guess):
   0:	49 81 c7 70 01 00 00 	add    $0x170,%r15
   7:	4c 8d 35 16 ea a8 0e 	lea    0xea8ea16(%rip),%r14        # 0xea8ea24
   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 d4 ac a6 00       	call   0xa6acf4
  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 (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/29 13:55 upstream dc59e4fea9d8 6a0c72dc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in hci_send_cmd
2026/07/21 03:07 upstream 1590cf032971 de6a700d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in hci_send_cmd
2026/04/21 23:00 upstream b4e07588e743 9765efe0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in hci_send_cmd
2026/07/20 03:33 linux-next cc2b5f627e8c 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in hci_send_cmd
2026/05/05 23:18 linux-next 4cd074ae20bb 06e69a27 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in hci_send_cmd
2026/05/01 02:36 linux-next b9303e6bff70 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in hci_send_cmd
* Struck through repros no longer work on HEAD.