[syzbot] [bluetooth] KASAN: slab-use-after-free Read in process_one_work (2)

syzbot
2026-04-22T13:34:24Z

Hello,

syzbot found the following issue on:

HEAD commit: c7275b05bc42 Add linux-next specific files for 20260417
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14aac1ba580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac861e8185149d86
dashboard link: https://syzkaller.appspot.com/bug?extid=b6a688ec97f423efb8ab
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/02c64cb49b64/disk-c7275b05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2703650c5cda/vmlinux-c7275b05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4a9b28b754f3/bzImage-c7275b05.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b6a688ec97f423efb8ab@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
Read of size 1 at addr ffff8880318ca330 by task kworker/1:8/10951

CPU: 1 UID: 0 PID: 10951 Comm: kworker/1:8 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events l2cap_chan_timeout
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
__kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574
kasan_check_byte include/linux/kasan.h:402 [inline]
lock_acquire+0x84/0x350 kernel/locking/lockdep.c:5844
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
_raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
rt_mutex_slowunlock+0xb8/0x300 kernel/locking/rtmutex.c:1426
process_one_work+0x9a3/0x1710 kernel/workqueue.c:3312
process_scheduled_works kernel/workqueue.c:3403 [inline]
worker_thread+0xba8/0x11e0 kernel/workqueue.c:3489
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

Allocated by task 60:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x3a6/0x690 mm/slub.c:5415
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
l2cap_conn_add+0xaa/0x970 net/bluetooth/l2cap_core.c:7001
l2cap_connect_cfm+0x142/0x1560 net/bluetooth/l2cap_core.c:7378
hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]
hci_remote_features_evt+0x5b9/0x950 net/bluetooth/hci_event.c:3760
hci_event_func net/bluetooth/hci_event.c:7796 [inline]
hci_event_packet+0x6ab/0xef0 net/bluetooth/hci_event.c:7847
hci_rx_work+0x3ee/0x1040 net/bluetooth/hci_core.c:4077
process_one_work+0x9a3/0x1710 kernel/workqueue.c:3312
process_scheduled_works kernel/workqueue.c:3403 [inline]
worker_thread+0xba8/0x11e0 kernel/workqueue.c:3489
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 13989:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2689 [inline]
slab_free mm/slub.c:6246 [inline]
kfree+0x1c5/0x6c0 mm/slub.c:6561
hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]
hci_conn_hash_flush+0x10d/0x260 net/bluetooth/hci_conn.c:2734
hci_dev_close_sync+0x821/0x10e0 net/bluetooth/hci_sync.c:5368
hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]
hci_unregister_dev+0x21a/0x5a0 net/bluetooth/hci_core.c:2716
vhci_release+0x155/0x1b0 drivers/bluetooth/hci_vhci.c:690
__fput+0x461/0xa70 fs/file_table.c:510
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x70f/0x22c0 kernel/exit.c:975
do_group_exit+0x21b/0x2d0 kernel/exit.c:1117
get_signal+0x1284/0x1330 kernel/signal.c:3037
arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
insert_work+0x3d/0x330 kernel/workqueue.c:2226
__queue_work+0xcfd/0x1010 kernel/workqueue.c:2381
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1794 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x764/0x9f0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x1de/0x6d0 kernel/softirq.c:626
__do_softirq kernel/softirq.c:660 [inline]
run_ktimerd+0x69/0x100 kernel/softirq.c:1155
smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Second to last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
insert_work+0x3d/0x330 kernel/workqueue.c:2226
__queue_work+0xbdb/0x1010 kernel/workqueue.c:2385
queue_work_on+0x106/0x1d0 kernel/workqueue.c:2432
queue_work include/linux/workqueue.h:696 [inline]
l2cap_conn_ready net/bluetooth/l2cap_core.c:1660 [inline]
l2cap_connect_cfm+0x10f5/0x1560 net/bluetooth/l2cap_core.c:7419
hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]
hci_remote_features_evt+0x5b9/0x950 net/bluetooth/hci_event.c:3760
hci_event_func net/bluetooth/hci_event.c:7796 [inline]
hci_event_packet+0x6ab/0xef0 net/bluetooth/hci_event.c:7847
hci_rx_work+0x3ee/0x1040 net/bluetooth/hci_core.c:4077
process_one_work+0x9a3/0x1710 kernel/workqueue.c:3312
process_scheduled_works kernel/workqueue.c:3403 [inline]
worker_thread+0xba8/0x11e0 kernel/workqueue.c:3489
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff8880318ca000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 816 bytes inside of
freed 1024-byte region [ffff8880318ca000, ffff8880318ca400)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880318cf800 pfn:0x318c8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000240(workingset|head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000240 ffff88813fe0fdc0 ffffea00007db010 ffffea0001ad2610
raw: ffff8880318cf800 000000080010000e 00000000f5000000 0000000000000000
head: 0080000000000240 ffff88813fe0fdc0 ffffea00007db010 ffffea0001ad2610
head: ffff8880318cf800 000000080010000e 00000000f5000000 0000000000000000
head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 17176054733, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
prep_new_page mm/page_alloc.c:1866 [inline]
get_page_from_freelist+0x27d6/0x2850 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
alloc_slab_page mm/slub.c:3278 [inline]
allocate_slab+0x77/0x660 mm/slub.c:3467
new_slab mm/slub.c:3525 [inline]
refill_objects+0x33c/0x3d0 mm/slub.c:7251
refill_sheaf mm/slub.c:2816 [inline]
__pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
alloc_from_pcs mm/slub.c:4749 [inline]
slab_alloc_node mm/slub.c:4883 [inline]
__kmalloc_cache_noprof+0x44e/0x690 mm/slub.c:5410
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
comedi_alloc_board_minor+0x57/0x530 drivers/comedi/comedi_fops.c:3510
comedi_init+0x109/0x1c0 drivers/comedi/comedi_fops.c:3664
do_one_initcall+0x250/0x870 init/main.c:1392
do_initcall_level+0x104/0x190 init/main.c:1454
do_initcalls+0x59/0xa0 init/main.c:1470
kernel_init_freeable+0x2a6/0x3e0 init/main.c:1703
kernel_init+0x1d/0x1d0 init/main.c:1593
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page_owner free stack trace missing

Memory state around the buggy address:
ffff8880318ca200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880318ca280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880318ca300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880318ca380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880318ca400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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