[syzbot] [kernel?] possible deadlock in alarm_handle_timer

From: syzbot
Date: Fri Nov 17 2023 - 09:13:34 EST


Hello,

syzbot found the following issue on:

HEAD commit: eff99d8edbed Add linux-next specific files for 20231117
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=134b7d84e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=61991b2630c19677
dashboard link: https://syzkaller.appspot.com/bug?extid=f2c4e7bfcca6c6d6324c
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/727bd99b8512/disk-eff99d8e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4a535e264e50/vmlinux-eff99d8e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/23c31e53f4d8/bzImage-eff99d8e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f2c4e7bfcca6c6d6324c@xxxxxxxxxxxxxxxxxxxxxxxxx

========================================================
WARNING: possible irq lock inversion dependency detected
6.7.0-rc1-next-20231117-syzkaller #0 Not tainted
--------------------------------------------------------
syz-executor.0/11087 just changed the state of lock:
ffff88801aba41b0 (&new_timer->it_lock){-...}-{2:2}, at: alarm_handle_timer+0x2d/0x2e0 kernel/time/alarmtimer.c:579
but this lock took another, HARDIRQ-unsafe lock in the past:
(&sighand->siglock){+.+.}-{2:2}


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(&sighand->siglock);
local_irq_disable();
lock(&new_timer->it_lock);
lock(&sighand->siglock);
<Interrupt>
lock(&new_timer->it_lock);

*** DEADLOCK ***

no locks held by syz-executor.0/11087.

the shortest dependencies between 2nd lock and 1st lock:
-> (&sighand->siglock){+.+.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
class_spinlock_constructor include/linux/spinlock.h:530 [inline]
ptrace_set_stopped kernel/ptrace.c:391 [inline]
ptrace_attach+0x401/0x650 kernel/ptrace.c:478
__do_sys_ptrace+0x204/0x230 kernel/ptrace.c:1290
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a
SOFTIRQ-ON-W at:
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
class_spinlock_constructor include/linux/spinlock.h:530 [inline]
ptrace_set_stopped kernel/ptrace.c:391 [inline]
ptrace_attach+0x401/0x650 kernel/ptrace.c:478
__do_sys_ptrace+0x204/0x230 kernel/ptrace.c:1290
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a
INITIAL USE at:
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0x36/0x50 kernel/locking/spinlock.c:170
spin_lock_irq include/linux/spinlock.h:376 [inline]
calculate_sigpending+0x44/0xa0 kernel/signal.c:197
ret_from_fork+0x23/0x80 arch/x86/kernel/process.c:143
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
}
... key at: [<ffffffff90b4af80>] __key.341+0x0/0x40
... acquired at:
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
__do_sys_timer_delete kernel/time/posix-timers.c:1023 [inline]
__se_sys_timer_delete kernel/time/posix-timers.c:1006 [inline]
__x64_sys_timer_delete+0x16a/0x3e0 kernel/time/posix-timers.c:1006
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a

-> (&new_timer->it_lock){-...}-{2:2} {
IN-HARDIRQ-W at:
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
alarm_handle_timer+0x2d/0x2e0 kernel/time/alarmtimer.c:579
alarmtimer_fired+0x132/0x550 kernel/time/alarmtimer.c:209
__run_hrtimer kernel/time/hrtimer.c:1688 [inline]
__hrtimer_run_queues+0x20c/0xc20 kernel/time/hrtimer.c:1752
hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1065 [inline]
__sysvec_apic_timer_interrupt+0x10c/0x410 arch/x86/kernel/apic/apic.c:1082
sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1076
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
_raw_spin_unlock_irqrestore+0x31/0x70 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
unlock_timer kernel/time/posix-timers.c:128 [inline]
do_timer_settime+0x260/0x2f0 kernel/time/posix-timers.c:934
__do_sys_timer_settime kernel/time/posix-timers.c:954 [inline]
__se_sys_timer_settime kernel/time/posix-timers.c:940 [inline]
__x64_sys_timer_settime+0x266/0x2c0 kernel/time/posix-timers.c:940
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a
INITIAL USE at:
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
__lock_timer+0x20d/0x4c0 kernel/time/posix-timers.c:595
__do_sys_timer_delete kernel/time/posix-timers.c:1011 [inline]
__se_sys_timer_delete kernel/time/posix-timers.c:1006 [inline]
__x64_sys_timer_delete+0x9e/0x3e0 kernel/time/posix-timers.c:1006
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a
}
... key at: [<ffffffff9280bea0>] __key.0+0x0/0x40
... acquired at:
mark_usage kernel/locking/lockdep.c:4563 [inline]
__lock_acquire+0x1347/0x3b10 kernel/locking/lockdep.c:5090
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
alarm_handle_timer+0x2d/0x2e0 kernel/time/alarmtimer.c:579
alarmtimer_fired+0x132/0x550 kernel/time/alarmtimer.c:209
__run_hrtimer kernel/time/hrtimer.c:1688 [inline]
__hrtimer_run_queues+0x20c/0xc20 kernel/time/hrtimer.c:1752
hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1065 [inline]
__sysvec_apic_timer_interrupt+0x10c/0x410 arch/x86/kernel/apic/apic.c:1082
sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1076
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
_raw_spin_unlock_irqrestore+0x31/0x70 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
unlock_timer kernel/time/posix-timers.c:128 [inline]
do_timer_settime+0x260/0x2f0 kernel/time/posix-timers.c:934
__do_sys_timer_settime kernel/time/posix-timers.c:954 [inline]
__se_sys_timer_settime kernel/time/posix-timers.c:940 [inline]
__x64_sys_timer_settime+0x266/0x2c0 kernel/time/posix-timers.c:940
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a


stack backtrace:
CPU: 1 PID: 11087 Comm: syz-executor.0 Not tainted 6.7.0-rc1-next-20231117-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
print_irq_inversion_bug.part.0+0x3e1/0x590 kernel/locking/lockdep.c:4079
print_irq_inversion_bug kernel/locking/lockdep.c:4032 [inline]
check_usage_forwards kernel/locking/lockdep.c:4110 [inline]
mark_lock_irq kernel/locking/lockdep.c:4242 [inline]
mark_lock+0x570/0xc50 kernel/locking/lockdep.c:4677
mark_usage kernel/locking/lockdep.c:4563 [inline]
__lock_acquire+0x1347/0x3b10 kernel/locking/lockdep.c:5090
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
alarm_handle_timer+0x2d/0x2e0 kernel/time/alarmtimer.c:579
alarmtimer_fired+0x132/0x550 kernel/time/alarmtimer.c:209
__run_hrtimer kernel/time/hrtimer.c:1688 [inline]
__hrtimer_run_queues+0x20c/0xc20 kernel/time/hrtimer.c:1752
hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1065 [inline]
__sysvec_apic_timer_interrupt+0x10c/0x410 arch/x86/kernel/apic/apic.c:1082
sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1076
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x70 kernel/locking/spinlock.c:194
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 16 c8 e3 f6 48 89 df e8 ce 3f e4 f6 f7 c5 00 02 00 00 75 1f 9c 58 f6 c4 02 75 2f <bf> 01 00 00 00 e8 85 ed d5 f6 65 8b 05 a6 18 7f 75 85 c0 74 12 5b
RSP: 0018:ffffc900037cfd70 EFLAGS: 00000246
RAX: 0000000000000002 RBX: ffff88801aba4198 RCX: 1ffffffff1e31619
RDX: 0000000000000000 RSI: ffffffff8accbfe0 RDI: ffffffff8b2f1520
RBP: 0000000000000287 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8f18e357 R11: 0000000000000001 R12: 0000000000000000
R13: 1ffff920006f9fb3 R14: ffffffff81789850 R15: dffffc0000000000
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
unlock_timer kernel/time/posix-timers.c:128 [inline]
do_timer_settime+0x260/0x2f0 kernel/time/posix-timers.c:934
__do_sys_timer_settime kernel/time/posix-timers.c:954 [inline]
__se_sys_timer_settime kernel/time/posix-timers.c:940 [inline]
__x64_sys_timer_settime+0x266/0x2c0 kernel/time/posix-timers.c:940
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a
RIP: 0033:0x7fac7f47cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fac8025f0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000df
RAX: ffffffffffffffda RBX: 00007fac7f59c050 RCX: 00007fac7f47cae9
RDX: 000000002006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fac7f4c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fac7f59c050 R15: 00007ffd40edc0c8
</TASK>
----------------
Code disassembly (best guess):
0: f5 cmc
1: 53 push %rbx
2: 48 8b 74 24 10 mov 0x10(%rsp),%rsi
7: 48 89 fb mov %rdi,%rbx
a: 48 83 c7 18 add $0x18,%rdi
e: e8 16 c8 e3 f6 call 0xf6e3c829
13: 48 89 df mov %rbx,%rdi
16: e8 ce 3f e4 f6 call 0xf6e43fe9
1b: f7 c5 00 02 00 00 test $0x200,%ebp
21: 75 1f jne 0x42
23: 9c pushf
24: 58 pop %rax
25: f6 c4 02 test $0x2,%ah
28: 75 2f jne 0x59
* 2a: bf 01 00 00 00 mov $0x1,%edi <-- trapping instruction
2f: e8 85 ed d5 f6 call 0xf6d5edb9
34: 65 8b 05 a6 18 7f 75 mov %gs:0x757f18a6(%rip),%eax # 0x757f18e1
3b: 85 c0 test %eax,%eax
3d: 74 12 je 0x51
3f: 5b pop %rbx


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