Hello,
syzbot has tested the proposed patch but the reproducer still triggered
crash:
INFO: task hung in wdm_flush
INFO: task syz-executor.1:2841 blocked for more than 143 seconds.
Not tainted 5.3.0-rc5+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1 D28520 2841 1862 0x00000004
Call Trace:
schedule+0x9a/0x250 kernel/sched/core.c:3944
wdm_flush+0x18a/0x460 drivers/usb/class/cdc-wdm.c:590
filp_close+0xb4/0x160 fs/open.c:1166
__close_fd+0x133/0x200 fs/file.c:636
__do_sys_close fs/open.c:1185 [inline]
__se_sys_close fs/open.c:1183 [inline]
__x64_sys_close+0x69/0x100 fs/open.c:1183
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413511
Code: 48 8b 40 30 83 80 00 01 00 00 ff 48 8b 6c 24 20 48 83 c4 28 c3 48 8d
05 07 31 24 00 48 89 04 24 48 c7 44 24 08 16 00 00 00 e8 <1b> 57 01 00 0f
0b 48 8d 05 15 00 22 00 48 89 04 24 48 c7 44 24 08
RSP: 002b:00007ffc1111a550 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000413511
RDX: fffffffffffffff7 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffc1111a630 R11: 0000000000000293 R12: 000000000075bf20
R13: 000000000000a6c3 R14: 0000000000760488 R15: ffffffffffffffff
INFO: task syz-executor.5:2855 blocked for more than 143 seconds.
Not tainted 5.3.0-rc5+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D28168 2855 1871 0x00000004
Call Trace:
schedule+0x9a/0x250 kernel/sched/core.c:3944
wdm_flush+0x18a/0x460 drivers/usb/class/cdc-wdm.c:590
filp_close+0xb4/0x160 fs/open.c:1166
__close_fd+0x133/0x200 fs/file.c:636
__do_sys_close fs/open.c:1185 [inline]
__se_sys_close fs/open.c:1183 [inline]
__x64_sys_close+0x69/0x100 fs/open.c:1183
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413511
Code: 48 8b 40 30 83 80 00 01 00 00 ff 48 8b 6c 24 20 48 83 c4 28 c3 48 8d
05 07 31 24 00 48 89 04 24 48 c7 44 24 08 16 00 00 00 e8 <1b> 57 01 00 0f
0b 48 8d 05 15 00 22 00 48 89 04 24 48 c7 44 24 08
RSP: 002b:00007fff97397960 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000413511
RDX: fffffffffffffff7 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007fff97397a40 R11: 0000000000000293 R12: 000000000075bf20
R13: 000000000000a894 R14: 0000000000760488 R15: ffffffffffffffff
Showing all locks held in the system:
1 lock held by khungtaskd/23:
#0: 0000000084b787af (rcu_read_lock){....}, at:
debug_show_all_locks+0x53/0x269 kernel/locking/lockdep.c:5254
1 lock held by rsyslogd/1604:
2 locks held by getty/1694:
#0: 000000001a489867 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 00000000a1f14aef (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1695:
#0: 00000000b6d2253c (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 000000006c54f9ae (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1696:
#0: 00000000393fdbe8 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 00000000946abfea (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1697:
#0: 00000000b4d6d459 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 00000000b782f4b1 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1698:
#0: 000000005059df5d (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 000000009805da5f (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1699:
#0: 00000000bed26f3a (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 000000004ed38206 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1700:
#0: 0000000040122501 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 00000000ddb347fb (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: khungtaskd Not tainted 5.3.0-rc5+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x55/0x96 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b0/0x1c7 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
watchdog+0x9a4/0xe50 kernel/hung_task.c:289
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt
arch/x86/include/asm/irqflags.h:60 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt
arch/x86/include/asm/irqflags.h:103 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0x28/0x2e0
arch/x86/kernel/process.c:580
Tested on:
commit: e06ce4da usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1767eb4a600000
kernel config: https://syzkaller.appspot.com/x/.config?x=d0c62209eedfd54e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=1667eb4a600000
