possible deadlock in free_ioctx_users

From: syzbot
Date: Sun Sep 09 2018 - 14:41:07 EST

Next message: Bart Van Assche: "Re: [PATCH] percpu-refcount: relax limit on percpu_ref_reinit()"
Previous message: Eric Dumazet: "Re: [PATCH] net/sock: move memory_allocated over to percpu_counter variables"
Next in thread: Matthew Wilcox: "Re: possible deadlock in free_ioctx_users"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello,

syzbot found the following crash on:

HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d86c4426a01f60feddc7@xxxxxxxxxxxxxxxxxxxxxxxxx

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)

========================================================
WARNING: possible irq lock inversion dependency detected
4.19.0-rc2+ #229 Not tainted
--------------------------------------------------------
swapper/0/0 just changed the state of lock:
00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline]
00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0xbc/0x710 fs/aio.c:603
but this lock took another, SOFTIRQ-unsafe lock in the past:
(&fiq->waitq){+.+.}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&fiq->waitq);
local_irq_disable();
lock(&(&ctx->ctx_lock)->rlock);
lock(&fiq->waitq);
<Interrupt>
lock(&(&ctx->ctx_lock)->rlock);

*** DEADLOCK ***

2 locks held by swapper/0/0:
#0: 0000000077c9a56b (rcu_callback){....}, at: __rcu_reclaim kernel/rcu/rcu.h:226 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: rcu_do_batch kernel/rcu/tree.c:2576 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: __rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: rcu_process_callbacks+0x1012/0x2670 kernel/rcu/tree.c:2864
#1: 0000000031dcf310 (rcu_read_lock_sched){....}, at: percpu_ref_call_confirm_rcu lib/percpu-refcount.c:119 [inline]
#1: 0000000031dcf310 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x2b7/0x820 lib/percpu-refcount.c:158

the shortest dependencies between 2nd lock and 1st lock:
-> (&fiq->waitq){+.+.} ops: 4 {
HARDIRQ-ON-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
fuse_request_send_background_locked+0x2f5/0x5a0 fs/fuse/dev.c:598
fuse_request_send_background+0x135/0x180 fs/fuse/dev.c:606
cuse_send_init fs/fuse/cuse.c:458 [inline]
cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12bf/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
SOFTIRQ-ON-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
fuse_request_send_background_locked+0x2f5/0x5a0 fs/fuse/dev.c:598
fuse_request_send_background+0x135/0x180 fs/fuse/dev.c:606
cuse_send_init fs/fuse/cuse.c:458 [inline]
cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12bf/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
fuse_request_send_background_locked+0x2f5/0x5a0 fs/fuse/dev.c:598
fuse_request_send_background+0x135/0x180 fs/fuse/dev.c:606
cuse_send_init fs/fuse/cuse.c:458 [inline]
cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12bf/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8b4763c0>] __key.42168+0x0/0x40
... acquired at:
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
aio_poll+0x760/0x1420 fs/aio.c:1747
io_submit_one+0xab8/0x1090 fs/aio.c:1850
__do_sys_io_submit fs/aio.c:1916 [inline]
__se_sys_io_submit fs/aio.c:1887 [inline]
__x64_sys_io_submit+0x1b9/0x5d0 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> (&(&ctx->ctx_lock)->rlock){..-.} ops: 2 {
IN-SOFTIRQ-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0xbc/0x710 fs/aio.c:603
percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:153 [inline]
do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
rest_init+0xe2/0xe5 init/main.c:442
start_kernel+0x8f4/0x92f init/main.c:739
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
aio_poll+0x738/0x1420 fs/aio.c:1746
io_submit_one+0xab8/0x1090 fs/aio.c:1850
__do_sys_io_submit fs/aio.c:1916 [inline]
__se_sys_io_submit fs/aio.c:1887 [inline]
__x64_sys_io_submit+0x1b9/0x5d0 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8b3dc960>] __key.50120+0x0/0x40
... acquired at:
mark_lock_irq kernel/locking/lockdep.c:2756 [inline]
mark_lock+0xa6b/0x1cb0 kernel/locking/lockdep.c:3128
mark_irqflags kernel/locking/lockdep.c:3006 [inline]
__lock_acquire+0x15f8/0x4ec0 kernel/locking/lockdep.c:3369
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0xbc/0x710 fs/aio.c:603
percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:153 [inline]
do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
rest_init+0xe2/0xe5 init/main.c:442
start_kernel+0x8f4/0x92f init/main.c:739
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc2+ #229
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
print_irq_inversion_bug.part.35+0x2c7/0x2d6 kernel/locking/lockdep.c:2622
print_irq_inversion_bug kernel/locking/lockdep.c:2625 [inline]
check_usage_forwards.cold.57+0x20/0x29 kernel/locking/lockdep.c:2647
mark_lock_irq kernel/locking/lockdep.c:2756 [inline]
mark_lock+0xa6b/0x1cb0 kernel/locking/lockdep.c:3128
mark_irqflags kernel/locking/lockdep.c:3006 [inline]
__lock_acquire+0x15f8/0x4ec0 kernel/locking/lockdep.c:3369
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0xbc/0x710 fs/aio.c:603
percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
</IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
Code: e9 2c ff ff ff 48 89 c7 48 89 45 d8 e8 43 b9 02 fa 48 8b 45 d8 e9 ca fe ff ff 48 89 df e8 32 b9 02 fa eb 82 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 90 90 90 90 90
RSP: 0018:ffffffff89407bb8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 1ffffffff1280f7b RCX: 0000000000000000
RDX: 1ffffffff12a4538 RSI: 0000000000000001 RDI: ffffffff895229c0
RBP: ffffffff89407bb8 R08: ffffffff89475fc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff89407c78
R13: ffffffff8a3149a0 R14: 0000000000000000 R15: 0000000000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:153 [inline]
do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
rest_init+0xe2/0xe5 init/main.c:442
start_kernel+0x8f4/0x92f init/main.c:739
? early_idt_handler_common+

---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Next message: Bart Van Assche: "Re: [PATCH] percpu-refcount: relax limit on percpu_ref_reinit()"
Previous message: Eric Dumazet: "Re: [PATCH] net/sock: move memory_allocated over to percpu_counter variables"
Next in thread: Matthew Wilcox: "Re: possible deadlock in free_ioctx_users"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]