[syzbot] [kernel?] inconsistent lock state in __lock_task_sighand

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f31817cbcf48 Add linux-next specific files for 20231116
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14d9b938e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f59345f1d0a928c
dashboard link: https://syzkaller.appspot.com/bug?extid=cf93299f5a30fb4c3829
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/987488cb251e/disk-f31817cb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6d4a82d8bd4b/vmlinux-f31817cb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc43dee9cb86/bzImage-f31817cb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf9329...@syzkaller.appspotmail.com

================================
WARNING: inconsistent lock state
6.7.0-rc1-next-20231116-syzkaller #0 Not tainted
--------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
syz-executor.5/8605 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff888037a9c0d8 (&sighand->siglock){?.+.}-{2:2}, at: __lock_task_sighand+0xc2/0x340 kernel/signal.c:1422
{HARDIRQ-ON-W} state was registered 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
irq event stamp: 100
hardirqs last enabled at (99): [<ffffffff8a84a34e>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last enabled at (99): [<ffffffff8a84a34e>] _raw_spin_unlock_irqrestore+0x4e/0x70 kernel/locking/spinlock.c:194
hardirqs last disabled at (100): [<ffffffff8a81011e>] sysvec_apic_timer_interrupt+0xe/0xb0 arch/x86/kernel/apic/apic.c:1076
softirqs last enabled at (0): [<ffffffff814d679c>] copy_process+0x244c/0x9770 kernel/fork.c:2466
softirqs last disabled at (0): [<0000000000000000>] 0x0

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

CPU0
----
lock(&sighand->siglock);
<Interrupt>
lock(&sighand->siglock);

*** DEADLOCK ***

3 locks held by syz-executor.5/8605:
#0: ffff88801d3321b0 (&new_timer->it_lock){-...}-{2:2}, at: posix_timer_fn+0x2d/0x3d0 kernel/time/posix-timers.c:318
#1: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
#1: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#1: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: send_sigqueue+0x10c/0x840 kernel/signal.c:1978
#2: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
#2: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#2: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x3f/0x340 kernel/signal.c:1405

stack backtrace:
CPU: 0 PID: 8605 Comm: syz-executor.5 Not tainted 6.7.0-rc1-next-20231116-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_usage_bug kernel/locking/lockdep.c:3970 [inline]
valid_state kernel/locking/lockdep.c:4012 [inline]
mark_lock_irq kernel/locking/lockdep.c:4215 [inline]
mark_lock+0x91a/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
__lock_task_sighand+0xc2/0x340 kernel/signal.c:1422
lock_task_sighand include/linux/sched/signal.h:748 [inline]
send_sigqueue+0x1d4/0x840 kernel/signal.c:1996
posix_timer_event kernel/time/posix-timers.c:298 [inline]
posix_timer_fn+0x181/0x3d0 kernel/time/posix-timers.c:324
__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 f6 c8 e3 f6 48 89 df e8 ae 40 e4 f6 f7 c5 00 02 00 00 75 1f 9c 58 f6 c4 02 75 2f <bf> 01 00 00 00 e8 65 ee d5 f6 65 8b 05 86 19 7f 75 85 c0 74 12 5b
RSP: 0018:ffffc9000a037d70 EFLAGS: 00000246
RAX: 0000000000000006 RBX: ffff88801d332198 RCX: 1ffffffff1e315d1
RDX: 0000000000000000 RSI: ffffffff8accbfe0 RDI: ffffffff8b2f13e0
RBP: 0000000000000287 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8f18e117 R11: 0000000000000002 R12: 0000000000000000
R13: 1ffff92001406fb3 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: 0033:0x7fc1e4a7cae9
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:00007fc1e57d40c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000df
RAX: ffffffffffffffda RBX: 00007fc1e4b9c120 RCX: 00007fc1e4a7cae9
RDX: 0000000020000340 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fc1e4ac847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fc1e4b9c120 R15: 00007ffd3001cd48
</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 f6 c8 e3 f6 call 0xf6e3c909
13: 48 89 df mov %rbx,%rdi
16: e8 ae 40 e4 f6 call 0xf6e440c9
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 65 ee d5 f6 call 0xf6d5ee99
34: 65 8b 05 86 19 7f 75 mov %gs:0x757f1986(%rip),%eax # 0x757f19c1
3b: 85 c0 test %eax,%eax
3d: 74 12 je 0x51
3f: 5b pop %rbx


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: f31817cbcf48 Add linux-next specific files for 20231116
git tree: linux-next

console+strace: https://syzkaller.appspot.com/x/log.txt?x=10037920e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=f59345f1d0a928c
dashboard link: https://syzkaller.appspot.com/bug?extid=cf93299f5a30fb4c3829
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13417498e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=107bb4b7680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/987488cb251e/disk-f31817cb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6d4a82d8bd4b/vmlinux-f31817cb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc43dee9cb86/bzImage-f31817cb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf9329...@syzkaller.appspotmail.com

================================
WARNING: inconsistent lock state
6.7.0-rc1-next-20231116-syzkaller #0 Not tainted
--------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.

syz-executor325/5066 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff888027362e58 (&sighand->siglock){?.+.}-{2:2}, at: __lock_task_sighand+0xc2/0x340 kernel/signal.c:1422

{HARDIRQ-ON-W} state was registered 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

irq event stamp: 1126
hardirqs last enabled at (1125): [<ffffffff8a84a34e>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last enabled at (1125): [<ffffffff8a84a34e>] _raw_spin_unlock_irqrestore+0x4e/0x70 kernel/locking/spinlock.c:194
hardirqs last disabled at (1126): [<ffffffff8a81011e>] sysvec_apic_timer_interrupt+0xe/0xb0 arch/x86/kernel/apic/apic.c:1076
softirqs last enabled at (1092): [<ffffffff8a84cf61>] softirq_handle_end kernel/softirq.c:399 [inline]
softirqs last enabled at (1092): [<ffffffff8a84cf61>] __do_softirq+0x591/0x8d5 kernel/softirq.c:582
softirqs last disabled at (1053): [<ffffffff814fe835>] invoke_softirq kernel/softirq.c:427 [inline]
softirqs last disabled at (1053): [<ffffffff814fe835>] __irq_exit_rcu kernel/softirq.c:632 [inline]
softirqs last disabled at (1053): [<ffffffff814fe835>] irq_exit_rcu+0xb5/0x120 kernel/softirq.c:644

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

CPU0
----
lock(&sighand->siglock);
<Interrupt>
lock(&sighand->siglock);

*** DEADLOCK ***

3 locks held by syz-executor325/5066:
#0: ffff88801c996038 (&new_timer->it_lock){-...}-{2:2}, at: posix_timer_fn+0x2d/0x3d0 kernel/time/posix-timers.c:318

#1: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
#1: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#1: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: send_sigqueue+0x10c/0x840 kernel/signal.c:1978
#2: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
#2: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#2: ffffffff8cfad060 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x3f/0x340 kernel/signal.c:1405

stack backtrace:

CPU: 1 PID: 5066 Comm: syz-executor325 Not tainted 6.7.0-rc1-next-20231116-syzkaller #0

RSP: 0018:ffffc90003aefd70 EFLAGS: 00000246
RAX: 0000000000000006 RBX: ffff88801c996020 RCX: 1ffffffff1e315d1

RDX: 0000000000000000 RSI: ffffffff8accbfe0 RDI: ffffffff8b2f13e0

RBP: 0000000000000293 R08: 0000000000000001 R09: 0000000000000001

R10: ffffffff8f18e117 R11: 0000000000000002 R12: 0000000000000000

R13: 1ffff9200075dfb3 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: 0033:0x7f375844aa39
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffefc2c0208 EFLAGS: 00000246 ORIG_RAX: 00000000000000df
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f375844aa39
RDX: 0000000020000080 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 00007f37584bd5f0 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001

</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 f6 c8 e3 f6 call 0xf6e3c909
13: 48 89 df mov %rbx,%rdi
16: e8 ae 40 e4 f6 call 0xf6e440c9
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 65 ee d5 f6 call 0xf6d5ee99
34: 65 8b 05 86 19 7f 75 mov %gs:0x757f1986(%rip),%eax # 0x757f19c1
3b: 85 c0 test %eax,%eax
3d: 74 12 je 0x51
3f: 5b pop %rbx


---

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot has bisected this issue to:

commit 2d25a889601d2fbc87ec79b30ea315820f874b78
Author: Peter Zijlstra <pet...@infradead.org>
Date: Sun Sep 17 11:24:21 2023 +0000

ptrace: Convert ptrace_attach() to use lock guards

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=144ac400e80000
start commit: f31817cbcf48 Add linux-next specific files for 20231116
git tree: linux-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=164ac400e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=124ac400e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=f59345f1d0a928c
dashboard link: https://syzkaller.appspot.com/bug?extid=cf93299f5a30fb4c3829

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=125ac3c0e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12c4d797680000

Reported-by: syzbot+cf9329...@syzkaller.appspotmail.com
Fixes: 2d25a889601d ("ptrace: Convert ptrace_attach() to use lock guards")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection