possible deadlock in userfaultfd_release

From: syzbot
Date: Sat Oct 27 2018 - 09:18:30 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 345671ea0f92 Merge branch 'akpm' (patches from Andrew)
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1557ea33400000
kernel config: https://syzkaller.appspot.com/x/.config?x=5c0a49d2b5210087
dashboard link: https://syzkaller.appspot.com/bug?extid=53c0b767f7ca0dc0c451
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1111f2eb400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e874f5400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+53c0b767f7ca0dc0c451@xxxxxxxxxxxxxxxxxxxxxxxxx

========================================================
WARNING: possible irq lock inversion dependency detected
4.19.0+ #306 Not tainted
--------------------------------------------------------
syz-executor911/5551 just changed the state of lock:
00000000758a85c4 (&ctx->fault_pending_wqh){+.+.}, at: spin_lock include/linux/spinlock.h:329 [inline]
00000000758a85c4 (&ctx->fault_pending_wqh){+.+.}, at: userfaultfd_release+0x63e/0x8d0 fs/userfaultfd.c:909
but this lock was taken by another, SOFTIRQ-safe lock in the past:
(&(&ctx->ctx_lock)->rlock){..-.}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
Chain exists of:
&(&ctx->ctx_lock)->rlock --> &ctx->fd_wqh --> &ctx->fault_pending_wqh

Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&ctx->fault_pending_wqh);
local_irq_disable();
lock(&(&ctx->ctx_lock)->rlock);
lock(&ctx->fd_wqh);
<Interrupt>
lock(&(&ctx->ctx_lock)->rlock);

*** DEADLOCK ***

no locks held by syz-executor911/5551.

the shortest dependencies between 2nd lock and 1st lock:
-> (&(&ctx->ctx_lock)->rlock){..-.} {
IN-SOFTIRQ-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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:285 [inline]
percpu_ref_put include/linux/percpu-refcount.h:301 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x563/0x730 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:240 [inline]
rcu_do_batch kernel/rcu/tree.c:2437 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline]
rcu_process_callbacks+0x100a/0x1ac0 kernel/rcu/tree.c:2697
__do_softirq+0x308/0xb7e kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:801
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
arch_safe_halt arch/x86/include/asm/paravirt.h:151 [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+0x49b/0x5c0 kernel/sched/idle.c:262
cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:353
rest_init+0x243/0x372 init/main.c:442
arch_call_rest_init+0xe/0x1b
start_kernel+0xa1f/0xa5a init/main.c:744
x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:472
x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:451
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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+0xa49/0xf80 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+0x1b7/0x580 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8aed8b20>] __key.50665+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+0xa49/0xf80 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+0x1b7/0x580 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> (&ctx->fd_wqh){....} {
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
add_wait_queue+0x92/0x2b0 kernel/sched/wait.c:22
aio_poll_queue_proc+0xa1/0x100 fs/aio.c:1705
poll_wait include/linux/poll.h:47 [inline]
userfaultfd_poll+0xff/0x3a0 fs/userfaultfd.c:958
vfs_poll include/linux/poll.h:86 [inline]
aio_poll+0x6ad/0x1420 fs/aio.c:1740
io_submit_one+0xa49/0xf80 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+0x1b7/0x580 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8aed88a0>] __key.44286+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]
userfaultfd_ctx_read+0x4f3/0x2180 fs/userfaultfd.c:1033
userfaultfd_read+0x1e2/0x2c0 fs/userfaultfd.c:1191
__vfs_read+0x117/0x9b0 fs/read_write.c:416
vfs_read+0x17f/0x3c0 fs/read_write.c:452
ksys_read+0x101/0x260 fs/read_write.c:578
__do_sys_read fs/read_write.c:588 [inline]
__se_sys_read fs/read_write.c:586 [inline]
__x64_sys_read+0x73/0xb0 fs/read_write.c:586
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> (&ctx->fault_pending_wqh){+.+.} {
HARDIRQ-ON-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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]
userfaultfd_release+0x63e/0x8d0 fs/userfaultfd.c:909
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1ad6/0x26d0 kernel/exit.c:867
do_group_exit+0x177/0x440 kernel/exit.c:970
get_signal+0x8b0/0x1980 kernel/signal.c:2517
do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
SOFTIRQ-ON-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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]
userfaultfd_release+0x63e/0x8d0 fs/userfaultfd.c:909
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1ad6/0x26d0 kernel/exit.c:867
do_group_exit+0x177/0x440 kernel/exit.c:970
get_signal+0x8b0/0x1980 kernel/signal.c:2517
do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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]
userfaultfd_ctx_read+0x4f3/0x2180 fs/userfaultfd.c:1033
userfaultfd_read+0x1e2/0x2c0 fs/userfaultfd.c:1191
__vfs_read+0x117/0x9b0 fs/read_write.c:416
vfs_read+0x17f/0x3c0 fs/read_write.c:452
ksys_read+0x101/0x260 fs/read_write.c:578
__do_sys_read fs/read_write.c:588 [inline]
__se_sys_read fs/read_write.c:586 [inline]
__x64_sys_read+0x73/0xb0 fs/read_write.c:586
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8aed8960>] __key.44283+0x0/0x40
... acquired at:
mark_lock_irq kernel/locking/lockdep.c:2687 [inline]
mark_lock+0x9b5/0x1cd0 kernel/locking/lockdep.c:3059
mark_irqflags kernel/locking/lockdep.c:2955 [inline]
__lock_acquire+0xd15/0x4c20 kernel/locking/lockdep.c:3298
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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]
userfaultfd_release+0x63e/0x8d0 fs/userfaultfd.c:909
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1ad6/0x26d0 kernel/exit.c:867
do_group_exit+0x177/0x440 kernel/exit.c:970
get_signal+0x8b0/0x1980 kernel/signal.c:2517
do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

stack backtrace:
CPU: 0 PID: 5551 Comm: syz-executor911 Not tainted 4.19.0+ #306
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+0x244/0x39d lib/dump_stack.c:113
print_irq_inversion_bug.part.37+0x2c7/0x2d6 kernel/locking/lockdep.c:2553
print_irq_inversion_bug kernel/locking/lockdep.c:2556 [inline]
check_usage_backwards.cold.56+0x1d/0x26 kernel/locking/lockdep.c:2602
mark_lock_irq kernel/locking/lockdep.c:2687 [inline]
mark_lock+0x9b5/0x1cd0 kernel/locking/lockdep.c:3059
mark_irqflags kernel/locking/lockdep.c:2955 [inline]
__lock_acquire+0xd15/0x4c20 kernel/locking/lockdep.c:3298
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__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]
userfaultfd_release+0x63e/0x8d0 fs/userfaultfd.c:909
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1ad6/0x26d0 kernel/exit.c:867
do_group_exit+0x177/0x440 kernel/exit.c:970
get_signal+0x8b0/0x1980 kernel/signal.c:2517
do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440e99
Code: Bad RIP value.
RSP: 002b:00007ffd69bf8a18 EFLAGS: 00000217 ORIG_RAX: 0000000000000000
RAX: fffffffffffffe00 RBX: 0000000000000000 RCX: 0000000000440e99
RDX: 0000000000000064 RSI: 0000000020009f9c RDI: 0000000000000004
RBP: 0000000000000000 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000217 R12: 0000000000401de0
R13: 0000000000401e70 R14: 0000000000000000 R15: 0000000000000000

---
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Next message: Julia Lawall: "[PATCH 0/2] constify structures stored in fields of v4l2_subdev_ops structure"
Previous message: Boris Petkov: "Re: [PATCH] kdump, vmcoreinfo: Export sme_me_mask value to vmcoreinfo"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]