syzbot


WARNING in hci_conn_drop (4)

Status: upstream: reported on 2026/05/15 12:05
Subsystems: bluetooth
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+195b4c12c5b8c9a8eb8b@syzkaller.appspotmail.com
First crash: 18d, last: 15h51m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
0928259b-0b11-49b7-a98a-dc75a11edee6 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ✅ WARNING in hci_conn_drop (4) 2026/05/21 05:21 2026/05/21 05:21 2026/05/21 06:12 cf874a1cf36318c06202027159ddac14acf00db7
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bluetooth?] WARNING in hci_conn_drop (4) 0 (1) 2026/05/15 12:05
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in hci_conn_drop bluetooth -1 1 518d 514d 0/29 auto-obsoleted due to no activity on 2025/04/06 16:23
linux-5.15 WARNING in hci_conn_drop -1 3 598d 689d 0/3 auto-obsoleted due to no activity on 2025/01/16 13:59
upstream WARNING in hci_conn_drop (3) bluetooth -1 2 206d 238d 0/29 auto-obsoleted due to no activity on 2026/02/12 14:34
linux-6.1 WARNING in hci_conn_drop -1 1 703d 703d 0/3 auto-obsoleted due to no activity on 2024/10/03 23:48
upstream WARNING in hci_conn_drop (2) bluetooth -1 1 390d 386d 0/29 auto-obsoleted due to no activity on 2025/08/12 21:54

Sample crash report:
------------[ cut here ]------------
workqueue: cannot queue hci_conn_timeout on wq hci0
WARNING: kernel/workqueue.c:2298 at __queue_work+0xfd4/0x136c kernel/workqueue.c:2296, CPU#0: kworker/0:7/4814
Modules linked in:
CPU: 0 UID: 0 PID: 4814 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events l2cap_chan_timeout
pstate: 634000c5 (nZCv daIF +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __queue_work+0xfd4/0x136c kernel/workqueue.c:2296
lr : __queue_work+0xfd4/0x136c kernel/workqueue.c:2296
sp : ffff8000961a7870
x29: ffff8000961a78b0 x28: ffff8000961a7c40 x27: ffff0000d1bd7a88
x26: ffff0000d5251800 x25: 0000000000000008 x24: ffff0000d52519c0
x23: dfff800000000000 x22: ffff0000f237802c x21: ffff800089fbc000
x20: ffff00010f408a58 x19: ffff00010f408a40 x18: 1fffe00035c08220
x17: ffff80008897b000 x16: ffff800088a2dba0 x15: ffff0001ae04110c
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000ff0100 x9 : 684f4e8f0746b200
x8 : 684f4e8f0746b200 x7 : ffff80008047caa0 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000000 x3 : ffff8000802f1374
x2 : 0000000100000000 x1 : ffff0000f2378000 x0 : 0000000000000000
Call trace:
 __queue_work+0xfd4/0x136c kernel/workqueue.c:2296 (P)
 __queue_delayed_work+0xf4/0x2b4 kernel/workqueue.c:2560
 queue_delayed_work_on+0xcc/0x140 kernel/workqueue.c:2612
 queue_delayed_work include/linux/workqueue.h:713 [inline]
 hci_conn_drop+0x174/0x29c include/net/bluetooth/hci_core.h:1712
 l2cap_chan_del+0x220/0x48c net/bluetooth/l2cap_core.c:672
 l2cap_chan_close+0x3e4/0x5ac net/bluetooth/l2cap_core.c:-1
 l2cap_chan_timeout+0x120/0x29c net/bluetooth/l2cap_core.c:431
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x79c/0x1098 kernel/workqueue.c:3397
 worker_thread+0x754/0xba0 kernel/workqueue.c:3478
 kthread+0x2f8/0x3c8 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842
irq event stamp: 181526
hardirqs last  enabled at (181525): [<ffff8000867a27cc>] irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:507 [inline]
hardirqs last  enabled at (181525): [<ffff8000867a27cc>] arm64_exit_to_kernel_mode+0x80/0x94 arch/arm64/kernel/entry-common.c:62
hardirqs last disabled at (181526): [<ffff80008034e698>] queue_delayed_work_on+0x54/0x140 kernel/workqueue.c:2608
softirqs last  enabled at (181506): [<ffff800084b0d92c>] spin_unlock_bh include/linux/spinlock.h:396 [inline]
softirqs last  enabled at (181506): [<ffff800084b0d92c>] release_sock+0x150/0x228 net/core/sock.c:3825
softirqs last disabled at (181500): [<ffff800084b0d810>] spin_lock_bh include/linux/spinlock.h:348 [inline]
softirqs last disabled at (181500): [<ffff800084b0d810>] release_sock+0x34/0x228 net/core/sock.c:3812
---[ end trace 0000000000000000 ]---

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/29 18:13 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 4b4362973b6f 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in hci_conn_drop
2026/05/25 02:08 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 4b4362973b6f c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in hci_conn_drop
2026/05/12 18:59 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5cbb61bf4168 d5b1a17d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in hci_conn_drop
2026/05/11 11:57 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5cbb61bf4168 e6eb7c0b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in hci_conn_drop
* Struck through repros no longer work on HEAD.