syzbot


WARNING: held lock freed in bt_accept_dequeue

Status: upstream: reported on 2024/12/18 07:43
Subsystems: bluetooth
[Documentation on labels]
Reported-by: syzbot+4c5f0c6f8cc60159bdbf@syzkaller.appspotmail.com
First crash: 258d, last: 16d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bluetooth?] WARNING: held lock freed in bt_accept_dequeue 0 (1) 2024/12/18 07:43

Sample crash report:
=========================
WARNING: held lock freed!
6.16.0-syzkaller #0 Not tainted
-------------------------
syz.0.33/6095 is freeing memory ffff888057e1b000-ffff888057e1b7ff, with a lock still held there!
ffff888057e1b258 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline]
ffff888057e1b258 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: bt_accept_dequeue+0xfc/0x590 net/bluetooth/af_bluetooth.c:279
2 locks held by syz.0.33/6095:
 #0: ffff888075f56808 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
 #0: ffff888075f56808 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: __sock_release net/socket.c:646 [inline]
 #0: ffff888075f56808 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: sock_close+0x9b/0x240 net/socket.c:1391
 #1: ffff888057e1b258 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline]
 #1: ffff888057e1b258 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: bt_accept_dequeue+0xfc/0x590 net/bluetooth/af_bluetooth.c:279

stack backtrace:
CPU: 0 UID: 0 PID: 6095 Comm: syz.0.33 Not tainted 6.16.0-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_freed_lock_bug kernel/locking/lockdep.c:6688 [inline]
 debug_check_no_locks_freed+0x18b/0x1c0 kernel/locking/lockdep.c:6723
 slab_free_hook mm/slub.c:2309 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0xfd/0x440 mm/slub.c:4842
 sk_prot_free net/core/sock.c:2286 [inline]
 __sk_destruct+0x4e1/0x660 net/core/sock.c:2381
 bt_accept_dequeue+0x3ce/0x590 net/bluetooth/af_bluetooth.c:308
 l2cap_sock_cleanup_listen+0x2f/0x3e0 net/bluetooth/l2cap_sock.c:1451
 l2cap_sock_release+0x5d/0x1d0 net/bluetooth/l2cap_sock.c:1425
 __sock_release net/socket.c:647 [inline]
 sock_close+0xc3/0x240 net/socket.c:1391
 __fput+0x449/0xa70 fs/file_table.c:465
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x22e0 kernel/exit.c:964
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f31ee1c14a5
Code: Unable to access opcode bytes at 0x7f31ee1c147b.
RSP: 002b:00007f31eef3cf80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f31ee3b5fa0 RCX: 00007f31ee1c14a5
RDX: 00007f31eef3cfc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f31ee211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f31ee3b6038 R14: 00007f31ee3b5fa0 R15: 00007ffde105fd88
 </TASK>
==================================================================
BUG: KASAN: slab-use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
BUG: KASAN: slab-use-after-free in do_raw_spin_lock+0x23d/0x290 kernel/locking/spinlock_debug.c:115
Read of size 4 at addr ffff888057e1b1c4 by task syz.0.33/6095

CPU: 1 UID: 0 PID: 6095 Comm: syz.0.33 Not tainted 6.16.0-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
 do_raw_spin_lock+0x23d/0x290 kernel/locking/spinlock_debug.c:115
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 release_sock+0x2f/0x1f0 net/core/sock.c:3765
 bt_accept_dequeue+0x512/0x590 net/bluetooth/af_bluetooth.c:312
 l2cap_sock_cleanup_listen+0x2f/0x3e0 net/bluetooth/l2cap_sock.c:1451
 l2cap_sock_release+0x5d/0x1d0 net/bluetooth/l2cap_sock.c:1425
 __sock_release net/socket.c:647 [inline]
 sock_close+0xc3/0x240 net/socket.c:1391
 __fput+0x449/0xa70 fs/file_table.c:465
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x22e0 kernel/exit.c:964
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f31ee1c14a5
Code: Unable to access opcode bytes at 0x7f31ee1c147b.
RSP: 002b:00007f31eef3cf80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f31ee3b5fa0 RCX: 00007f31ee1c14a5
RDX: 00007f31eef3cfc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f31ee211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f31ee3b6038 R14: 00007f31ee3b5fa0 R15: 00007ffde105fd88
 </TASK>

Allocated by task 5840:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_noprof+0x27a/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 sk_prot_alloc+0xe7/0x220 net/core/sock.c:2247
 sk_alloc+0x3a/0x370 net/core/sock.c:2303
 bt_sock_alloc+0x3b/0x310 net/bluetooth/af_bluetooth.c:151
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1894 [inline]
 l2cap_sock_new_connection_cb+0xe2/0x2b0 net/bluetooth/l2cap_sock.c:1482
 l2cap_connect_cfm+0x377/0x1040 net/bluetooth/l2cap_core.c:7287
 hci_connect_cfm include/net/bluetooth/hci_core.h:2059 [inline]
 hci_remote_features_evt+0x584/0x8e0 net/bluetooth/hci_event.c:3712
 hci_event_func net/bluetooth/hci_event.c:7477 [inline]
 hci_event_packet+0x7e0/0x1200 net/bluetooth/hci_event.c:7531
 hci_rx_work+0x46a/0xe80 net/bluetooth/hci_core.c:4070
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6095:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x18e/0x440 mm/slub.c:4842
 sk_prot_free net/core/sock.c:2286 [inline]
 __sk_destruct+0x4e1/0x660 net/core/sock.c:2381
 bt_accept_dequeue+0x3ce/0x590 net/bluetooth/af_bluetooth.c:308
 l2cap_sock_cleanup_listen+0x2f/0x3e0 net/bluetooth/l2cap_sock.c:1451
 l2cap_sock_release+0x5d/0x1d0 net/bluetooth/l2cap_sock.c:1425
 __sock_release net/socket.c:647 [inline]
 sock_close+0xc3/0x240 net/socket.c:1391
 __fput+0x449/0xa70 fs/file_table.c:465
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x22e0 kernel/exit.c:964
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888057e1b000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 452 bytes inside of
 freed 2048-byte region [ffff888057e1b000, ffff888057e1b800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x57e18
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a442000 ffffea0000cb6800 dead000000000002
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a442000 ffffea0000cb6800 dead000000000002
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea00015f8601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 5844, tgid 5844 (syz-executor), ts 85060310152, free_ts 24963019179
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 ieee80211_register_hw+0x1ebd/0x4120 net/mac80211/main.c:1357
 mac80211_hwsim_new_radio+0x2f0e/0x5340 drivers/net/wireless/virtual/mac80211_hwsim.c:5565
 hwsim_new_radio_nl+0xea4/0x1b10 drivers/net/wireless/virtual/mac80211_hwsim.c:6249
 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2552
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc65/0xe60 mm/page_alloc.c:2706
 __free_pages mm/page_alloc.c:5071 [inline]
 free_contig_range+0x1bd/0x4a0 mm/page_alloc.c:6927
 destroy_args+0x7e/0x5d0 mm/debug_vm_pgtable.c:1009
 debug_vm_pgtable+0x412/0x450 mm/debug_vm_pgtable.c:1389
 do_one_initcall+0x233/0x820 init/main.c:1274
 do_initcall_level+0x137/0x1f0 init/main.c:1336
 do_initcalls+0x69/0xd0 init/main.c:1352
 kernel_init_freeable+0x3d9/0x570 init/main.c:1584
 kernel_init+0x1d/0x1d0 init/main.c:1474
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888057e1b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888057e1b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888057e1b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888057e1b200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888057e1b280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/13 10:28 upstream 038d61fd6422 22ec1469 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: held lock freed in bt_accept_dequeue
2025/01/03 23:23 upstream 0bc21e701a6f f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING: held lock freed in bt_accept_dequeue
2024/12/13 19:10 upstream 243f750a2df0 7cbfbb3a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: held lock freed in bt_accept_dequeue
2025/06/02 11:02 net 558428921edd 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: held lock freed in bt_accept_dequeue
2025/06/02 03:44 net 558428921edd 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: held lock freed in bt_accept_dequeue
2025/06/01 10:55 net 558428921edd 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: held lock freed in bt_accept_dequeue
2025/06/01 02:15 net 558428921edd 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: held lock freed in bt_accept_dequeue
2025/05/01 17:32 net 2d52e2e38b85 51b137cd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: held lock freed in bt_accept_dequeue
2025/03/31 11:04 net-next 1a9239bb4253 d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: held lock freed in bt_accept_dequeue
* Struck through repros no longer work on HEAD.