Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_send_cmd

[syzbot <syzbot+31c2f641b850a348a734@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in disable_work_sync

INFO: task syz-executor:13931 blocked for more than 143 seconds.
      Not tainted 6.13.0-rc7-syzkaller-g619f0b6fad52-dirty #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:20544 pid:13931 tgid:13931 ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 __flush_work+0xa47/0xc60 kernel/workqueue.c:4242
 __cancel_work_sync kernel/workqueue.c:4362 [inline]
 disable_work_sync+0xba/0xe0 kernel/workqueue.c:4473
 hci_unregister_dev+0x149/0x510 net/bluetooth/hci_core.c:2687
 vhci_release+0x80/0xd0 drivers/bluetooth/hci_vhci.c:664
 __fput+0x23c/0xa50 fs/file_table.c:450
 task_work_run+0x24f/0x310 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa2a/0x28e0 kernel/exit.c:938
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3017
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1b7bf8453a
RSP: 002b:00007f1b7c29ecc8 EFLAGS: 00000286
 ORIG_RAX: 0000000000000106
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f1b7bf8453a
RDX: 00007f1b7c29ecf0 RSI: 00007f1b7c29ed80 RDI: 00000000ffffff9c
RBP: 00007f1b7c29ed80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000286 R12: 00007f1b7c29fe00
R13: 00007f1b7c0018f4 R14: 00007f1b7c29fe40 R15: 0000000000000258
 </TASK>
INFO: task syz-executor:14434 blocked for more than 144 seconds.
      Not tainted 6.13.0-rc7-syzkaller-g619f0b6fad52-dirty #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D
 stack:19936 pid:14434 tgid:14434 ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 __flush_work+0xa47/0xc60 kernel/workqueue.c:4242
 __cancel_work_sync kernel/workqueue.c:4362 [inline]
 disable_work_sync+0xba/0xe0 kernel/workqueue.c:4473
 hci_unregister_dev+0x149/0x510 net/bluetooth/hci_core.c:2687
 vhci_release+0x80/0xd0 drivers/bluetooth/hci_vhci.c:664
 __fput+0x23c/0xa50 fs/file_table.c:450
 task_work_run+0x24f/0x310 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa2a/0x28e0 kernel/exit.c:938
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3017
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9b86587a6a
RSP: 002b:00007f9b8689f6c8 EFLAGS: 00000212
 ORIG_RAX: 0000000000000037
RAX: 0000000000000000 RBX: 00007f9b8689f750 RCX: 00007f9b86587a6a
RDX: 0000000000000041 RSI: 0000000000000029 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007f9b8689f6ec R09: 0079746972756365
R10: 00007f9b8689f750 R11: 0000000000000212 R12: 00007f9b86746c80
R13: 00007f9b8689f6ec R14: 0000000000000000 R15: 00007f9b86748e40
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: 
ffffffff8e937ae0 (rcu_read_lock
){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744
3 locks held by kworker/u9:0/54:
 #0: ffff88805dbaa148
 ((wq_completion)hci3#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 ((wq_completion)hci3#2){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc90000be7d00
 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: 
ffffffff8fe23c88
 (l2cap_conn_del_lock){+.+.}-{4:4}, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
3 locks held by kworker/u9:1/5146:
 #0: 
ffff8880298ad148
 (
(wq_completion)hci10#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
(wq_completion)hci10#2){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc9000ecc7d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3212 [inline]
, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: ffffffff8fe23c88 (l2cap_conn_del_lock){+.+.}-{4:4}, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
2 locks held by getty/5588:
 #0: ffff88803160e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
3 locks held by kworker/u9:4/6605:
 #0: 
ffff88807a88d948
 (
(wq_completion)hci5
#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
#2){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc90003a17d00 ((work_completion)(&hdev->rx_work)
){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3212 [inline]
, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: ffffffff8fe23c88 (l2cap_conn_del_lock){+.+.}-{4:4}, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
3 locks held by kworker/u9:5/6607:
 #0: ffff8880794e8148 (
(wq_completion)hci7#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
(wq_completion)hci7#2){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: 
ffffc90003967d00
 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: 
ffffffff8fe23c88
 (l2cap_conn_del_lock){+.+.}-{4:4}
, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
3 locks held by kworker/u9:6/6609:
 #0: 
ffff88805b8a2148
 (
(wq_completion)hci9
#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
#2){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: 
ffffc90003c87d00
 (
(work_completion)(&hdev->rx_work)
){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3212 [inline]
, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: ffffffff8fe23c88 (l2cap_conn_del_lock){+.+.}-{4:4}, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
3 locks held by kworker/u9:7/6610:
 #0: 
ffff8880250d8148 ((wq_completion)hci1
#2
){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3211 [inline]
, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: 
ffffc90003a87d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3212 [inline]
, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: 
ffffffff8fe23c88
 (l2cap_conn_del_lock){+.+.}-{4:4}
, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
5 locks held by kworker/u9:8/14419:
3 locks held by kworker/u9:9/14841:
 #0: ffff8880794ed948
 ((wq_completion)hci6#2){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3211 [inline]
, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: 
ffffc9000c9f7d00
 ((work_completion)(&hdev->rx_work)
){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: 
ffffffff8fe23c88
 (l2cap_conn_del_lock
){+.+.}-{4:4}, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
3 locks held by kworker/u9:11/15620:
 #0: ffff88805dbae148
 (
(wq_completion)hci4#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
(wq_completion)hci4#2){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc9000cd17d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:3212 [inline]
, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: 
ffffffff8fe23c88
 (
l2cap_conn_del_lock
){+.+.}-{4:4}, at: l2cap_recv_acldata+0x79/0x1300 net/bluetooth/l2cap_core.c:7485
3 locks held by kworker/u9:12/22957:
4 locks held by syz-executor920/22964:

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-rc7-syzkaller-g619f0b6fad52-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xff6/0x1040 kernel/hung_task.c:397
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 14419 Comm: kworker/u9:8 Not tainted 6.13.0-rc7-syzkaller-g619f0b6fad52-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: hci8 hci_rx_work
RIP: 0010:io_serial_in+0x76/0xb0 drivers/tty/serial/8250/8250_port.c:409
Code: 10 2c 4f fc 89 e9 41 d3 e6 48 83 c3 40 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 31 96 b5 fc 44 03 33 44 89 f2 ec <0f> b6 c0 5b 41 5e 41 5f 5d c3 cc cc cc cc 89 e9 80 e1 07 38 c1 7c
RSP: 0018:ffffc9000dba6b98 EFLAGS: 00000002
RAX: 1ffffffff34de400 RBX: ffffffff9a6f27c0 RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: 0000000000000000 R08: ffffffff85505656 R09: 1ffff11004a5c046
R10: dffffc0000000000 R11: ffffffff85505610 R12: dffffc0000000000
R13: ffffffff9a3ecf70 R14: 00000000000003fd R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555578960788 CR3: 000000005b10e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:137 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:159 [inline]
 wait_for_lsr drivers/tty/serial/8250/8250_port.c:2088 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3335 [inline]
 serial8250_console_write+0x1373/0x1ed0 drivers/tty/serial/8250/8250_port.c:3413
 console_emit_next_record kernel/printk/printk.c:3122 [inline]
 console_flush_all+0x869/0xeb0 kernel/printk/printk.c:3210
 __console_flush_and_unlock kernel/printk/printk.c:3269 [inline]
 console_unlock+0x14f/0x3b0 kernel/printk/printk.c:3309
 vprintk_emit+0x730/0xa10 kernel/printk/printk.c:2432
 _printk+0xd5/0x120 kernel/printk/printk.c:2457
 bt_err+0x127/0x180 net/bluetooth/lib.c:296
 l2cap_sig_channel net/bluetooth/l2cap_core.c:5541 [inline]
 l2cap_recv_frame+0x21ba/0x10db0 net/bluetooth/l2cap_core.c:6821
 l2cap_recv_acldata+0x486/0x1300 net/bluetooth/l2cap_core.c:7515
 hci_acldata_packet net/bluetooth/hci_core.c:3797 [inline]
 hci_rx_work+0x508/0xdb0 net/bluetooth/hci_core.c:4040
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


Tested on:

commit:         619f0b6f Merge tag 'seccomp-v6.13-rc8' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a5ce64580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=aadf89e2f6db86cc
dashboard link: https://syzkaller.appspot.com/bug?extid=31c2f641b850a348a734
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11b789df980000