===================================== WARNING: bad unlock balance detected! syzkaller #0 Not tainted ------------------------------------- kworker/u5:0/144 is trying to release lock (&chan->lock) at: [] l2cap_chan_unlock include/net/bluetooth/l2cap.h:862 [inline] [] l2cap_conless_channel net/bluetooth/l2cap_core.c:7853 [inline] [] l2cap_recv_frame+0xeb4/0x74dc net/bluetooth/l2cap_core.c:7906 but there are no more locks to release! other info that might help us debug this: 2 locks held by kworker/u5:0/144: #0: ffff0000de1de938 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x678/0x1138 kernel/workqueue.c:2283 #1: ffff80001bed7c00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1138 kernel/workqueue.c:2285 stack backtrace: CPU: 1 PID: 144 Comm: kworker/u5:0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: hci0 hci_rx_work Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_unlock_imbalance_bug+0x11c/0x160 kernel/locking/lockdep.c:5065 __lock_release kernel/locking/lockdep.c:5302 [inline] lock_release+0x454/0x8e0 kernel/locking/lockdep.c:5643 __mutex_unlock_slowpath+0xc4/0x5e4 kernel/locking/mutex.c:851 mutex_unlock+0x90/0xec kernel/locking/mutex.c:536 l2cap_chan_unlock include/net/bluetooth/l2cap.h:862 [inline] l2cap_conless_channel net/bluetooth/l2cap_core.c:7853 [inline] l2cap_recv_frame+0xeb4/0x74dc net/bluetooth/l2cap_core.c:7906 l2cap_recv_acldata+0x4dc/0x1364 net/bluetooth/l2cap_core.c:8618 hci_acldata_packet net/bluetooth/hci_core.c:4977 [inline] hci_rx_work+0x3a0/0x868 net/bluetooth/hci_core.c:5169 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856 ================================================================== BUG: KASAN: use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:85 [inline] BUG: KASAN: use-after-free in do_raw_spin_lock+0x244/0x2fc kernel/locking/spinlock_debug.c:114 Read of size 4 at addr ffff0000e87c608c by task kworker/u5:0/144 CPU: 1 PID: 144 Comm: kworker/u5:0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: hci0 hci_rx_work Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 print_address_description+0x78/0x30c mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0xec/0x158 mm/kasan/report.c:451 __asan_report_load4_noabort+0x44/0x50 mm/kasan/report_generic.c:308 debug_spin_lock_before kernel/locking/spinlock_debug.c:85 [inline] do_raw_spin_lock+0x244/0x2fc kernel/locking/spinlock_debug.c:114 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:136 [inline] _raw_spin_lock_bh+0x11c/0x1b4 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:369 [inline] __lock_sock+0x114/0x264 net/core/sock.c:2707 lock_sock_nested+0x124/0x1d4 net/core/sock.c:3264 lock_sock include/net/sock.h:1744 [inline] l2cap_sock_recv_cb+0x5c/0x1c4 net/bluetooth/l2cap_sock.c:1502 l2cap_conless_channel net/bluetooth/l2cap_core.c:7852 [inline] l2cap_recv_frame+0xe08/0x74dc net/bluetooth/l2cap_core.c:7906 l2cap_recv_acldata+0x4dc/0x1364 net/bluetooth/l2cap_core.c:8618 hci_acldata_packet net/bluetooth/hci_core.c:4977 [inline] hci_rx_work+0x3a0/0x868 net/bluetooth/hci_core.c:5169 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856 Allocated by task 5530: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc+0xb0/0xf0 mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:264 [inline] __kmalloc+0x290/0x43c mm/slub.c:4412 kmalloc include/linux/slab.h:612 [inline] sk_prot_alloc+0xc4/0x1ec net/core/sock.c:1866 sk_alloc+0x40/0x384 net/core/sock.c:1922 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1870 [inline] l2cap_sock_create+0x140/0x350 net/bluetooth/l2cap_sock.c:1918 bt_sock_create+0x14c/0x24c net/bluetooth/af_bluetooth.c:130 __sock_create+0x4b0/0x8b4 net/socket.c:1495 sock_create net/socket.c:1551 [inline] __sys_socket+0xf0/0x18c net/socket.c:1593 __do_sys_socket net/socket.c:1602 [inline] __se_sys_socket net/socket.c:1600 [inline] __arm64_sys_socket+0x7c/0x94 net/socket.c:1600 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Freed by task 5529: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4c/0x84 mm/kasan/common.c:46 kasan_set_free_info+0x28/0x4c mm/kasan/generic.c:360 ____kasan_slab_free+0x118/0x164 mm/kasan/common.c:366 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1710 [inline] slab_free_freelist_hook+0x128/0x1e4 mm/slub.c:1736 slab_free mm/slub.c:3504 [inline] kfree+0x16c/0x400 mm/slub.c:4564 sk_prot_free net/core/sock.c:1905 [inline] __sk_destruct+0x43c/0x610 net/core/sock.c:1991 sk_destruct net/core/sock.c:2006 [inline] __sk_free+0x320/0x430 net/core/sock.c:2017 sk_free+0x68/0xd4 net/core/sock.c:2028 sock_put include/net/sock.h:1989 [inline] l2cap_sock_kill+0x114/0x21c net/bluetooth/l2cap_sock.c:1258 l2cap_sock_release+0x144/0x1bc net/bluetooth/l2cap_sock.c:1432 __sock_release net/socket.c:651 [inline] sock_close+0xb4/0x1f8 net/socket.c:1345 __fput+0x1c0/0x7e8 fs/file_table.c:311 ____fput+0x20/0x30 fs/file_table.c:339 task_work_run+0x12c/0x1d8 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] do_notify_resume+0x2450/0x309c arch/arm64/kernel/signal.c:949 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1d0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 The buggy address belongs to the object at ffff0000e87c6000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 140 bytes inside of 2048-byte region [ffff0000e87c6000, ffff0000e87c6800) The buggy address belongs to the page: page:00000000360f27ae refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1287c0 head:00000000360f27ae order:3 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 fffffc000323b800 0000000300000003 ffff0000c0002900 raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000e87c5f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000e87c6000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000e87c6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000e87c6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000e87c6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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