Re: [syzbot] KASAN: use-after-free Write in io_queue_worker_create

syzbot
2021-12-10T11:00:09Z

Hello,

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

INFO: task syz-executor.2:8594 blocked for more than 143 seconds.
Not tainted 5.16.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2 state:D stack:26928 pid: 8594 ppid: 3894 flags:0x00024004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:4972 [inline]
__schedule+0xa9a/0x4940 kernel/sched/core.c:6253
schedule+0xd2/0x260 kernel/sched/core.c:6326
schedule_timeout+0x1db/0x2a0 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x174/0x270 kernel/sched/completion.c:138
io_wq_exit_workers fs/io-wq.c:1222 [inline]
io_wq_put_and_exit+0x33a/0xb70 fs/io-wq.c:1257
io_uring_clean_tctx fs/io_uring.c:9803 [inline]
io_uring_cancel_generic+0x622/0x695 fs/io_uring.c:9886
io_uring_files_cancel include/linux/io_uring.h:16 [inline]
do_exit+0x60c/0x2b40 kernel/exit.c:787
do_group_exit+0x125/0x310 kernel/exit.c:929
get_signal+0x47d/0x2220 kernel/signal.c:2830
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fe940cbfb49
RSP: 002b:00007fe940435218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fe940dd2f68 RCX: 00007fe940cbfb49
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fe940dd2f68
RBP: 00007fe940dd2f60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe940dd2f6c
R13: 00007ffc1b1af90f R14: 00007fe940435300 R15: 0000000000022000
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8bb83a60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6458
2 locks held by getty/3278:
#0: ffff888023517098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:252
#1: ffffc90002b962e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcf0/0x1230 drivers/tty/n_tty.c:2113
2 locks held by kworker/u4:8/4544:
#0: ffff8880b9d39a98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2b/0x120 kernel/sched/core.c:478
#1: ffffc900038bfdb0 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work+0x8ca/0x1690 kernel/workqueue.c:2273

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0xc1d/0xf50 kernel/hung_task.c:295
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4355 Comm: kworker/u4:7 Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: phy12 ieee80211_iface_work
RIP: 0010:mark_lock+0x27/0x17b0 kernel/locking/lockdep.c:4566
Code: 00 00 90 41 57 41 56 41 55 41 54 41 89 d4 48 ba 00 00 00 00 00 fc ff df 55 53 48 81 ec 18 01 00 00 48 8d 5c 24 38 48 89 3c 24 <48> c7 44 24 38 b3 8a b5 41 48 c1 eb 03 48 c7 44 24 40 e0 66 37 8b
RSP: 0018:ffffc90002dbf380 EFLAGS: 00000082
RAX: 0000000000000004 RBX: ffffc90002dbf3b8 RCX: 1ffffffff1b228f1
RDX: dffffc0000000000 RSI: ffff88801d8fe160 RDI: ffff88801d8fd700
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff817e2bc8 R11: 0000000000000000 R12: 0000000000000002
R13: dffffc0000000000 R14: ffff88801d8fe160 R15: 000000000003d510
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055de5437a600 CR3: 000000000b88e000 CR4: 0000000000350ee0
Call Trace:
<TASK>
mark_held_locks+0x9f/0xe0 kernel/locking/lockdep.c:4206
__trace_hardirqs_on_caller kernel/locking/lockdep.c:4224 [inline]
lockdep_hardirqs_on_prepare kernel/locking/lockdep.c:4292 [inline]
lockdep_hardirqs_on_prepare+0x135/0x400 kernel/locking/lockdep.c:4244
trace_hardirqs_on+0x5b/0x1c0 kernel/trace/trace_preemptirq.c:49
___slab_alloc+0xc41/0xfe0 mm/slub.c:2978
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109
slab_alloc_node mm/slub.c:3200 [inline]
slab_alloc mm/slub.c:3242 [inline]
__kmalloc+0x2fb/0x340 mm/slub.c:4419
kmalloc include/linux/slab.h:595 [inline]
kzalloc include/linux/slab.h:724 [inline]
cfg80211_inform_single_bss_frame_data+0x302/0xee0 net/wireless/scan.c:2397
cfg80211_inform_bss_frame_data+0xa7/0xb50 net/wireless/scan.c:2458
ieee80211_bss_info_update+0x35b/0xb30 net/mac80211/scan.c:190
ieee80211_rx_bss_info net/mac80211/ibss.c:1119 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1610 [inline]
ieee80211_ibss_rx_queued_mgmt+0x19cf/0x3130 net/mac80211/ibss.c:1639
ieee80211_iface_process_skb net/mac80211/iface.c:1466 [inline]
ieee80211_iface_work+0xa65/0xd00 net/mac80211/iface.c:1520
process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298
worker_thread+0x658/0x11f0 kernel/workqueue.c:2445
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 90 nop
3: 41 57 push %r15
5: 41 56 push %r14
7: 41 55 push %r13
9: 41 54 push %r12
b: 41 89 d4 mov %edx,%r12d
e: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
15: fc ff df
18: 55 push %rbp
19: 53 push %rbx
1a: 48 81 ec 18 01 00 00 sub $0x118,%rsp
21: 48 8d 5c 24 38 lea 0x38(%rsp),%rbx
26: 48 89 3c 24 mov %rdi,(%rsp)
* 2a: 48 c7 44 24 38 b3 8a movq $0x41b58ab3,0x38(%rsp) <-- trapping instruction
31: b5 41
33: 48 c1 eb 03 shr $0x3,%rbx
37: 48 c7 44 24 40 e0 66 movq $0xffffffff8b3766e0,0x40(%rsp)
3e: 37 8b

Tested on:

commit: 02a3f9f3 io_uring: ensure task_work gets run as part o..
git tree: git://git.kernel.dk/linux-block io_uring-5.16
console output: https://syzkaller.appspot.com/x/log.txt?x=1037614db00000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d3b8fd1977c1e73
dashboard link: https://syzkaller.appspot.com/bug?extid=b60c982cb0efc5e05a47
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2