WARNING in posix_cpu_timer_del (3)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    6d028043 Add linux-next specific files for 20190830
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=179e59de600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=82a6bec43ab0cb69
dashboard link: https://syzkaller.appspot.com/bug?extid=dabf3198a30ed5a2158f
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13bb4546600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13af4356600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+dabf3198a30ed5a2158f@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
WARNING: CPU: 1 PID: 9805 at kernel/time/posix-cpu-timers.c:401  
posix_cpu_timer_del+0x2f0/0x3b0 kernel/time/posix-cpu-timers.c:401
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 9805 Comm: syz-executor380 Not tainted 5.3.0-rc6-next-20190830  
#75
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+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x2dc/0x755 kernel/panic.c:220
 __warn.cold+0x2f/0x3c kernel/panic.c:581
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:posix_cpu_timer_del+0x2f0/0x3b0 kernel/time/posix-cpu-timers.c:401
Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85  
b5 00 00 00 48 83 bb c8 00 00 00 00 74 16 e8 00 58 0d 00 <0f> 0b e9 87 fe  
ff ff e8 c4 38 48 00 e9 dd fd ff ff e8 ea 57 0d 00
RSP: 0018:ffff88809ac87a30 EFLAGS: 00010093
RAX: ffff888090a6e0c0 RBX: ffff88809ae762e0 RCX: 1ffff1101214dd2a
RDX: 0000000000000000 RSI: ffffffff8164fe10 RDI: ffff88809ae763a8
RBP: ffff88809ac87ac0 R08: 0000000000000002 R09: ffff888090a6e958
R10: fffffbfff138aef8 R11: ffffffff89c577c7 R12: ffff88809b326100
R13: 1ffff11013590f47 R14: ffff88809ac87a98 R15: ffff88809ae76338
 timer_delete_hook kernel/time/posix-timers.c:978 [inline]
 itimer_delete kernel/time/posix-timers.c:1021 [inline]
 exit_itimers+0xdb/0x2e0 kernel/time/posix-timers.c:1041
 do_exit+0x1980/0x2e60 kernel/exit.c:853
 do_group_exit+0x135/0x360 kernel/exit.c:983
 get_signal+0x47c/0x2500 kernel/signal.c:2734
 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446679
Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffff909e168 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 0000000000017a92 RCX: 0000000000446679
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc2c
RBP: 00000000006dbc2c R08: 000000037ffffa00 R09: 000000037ffffa00
R10: 00007ffff909e180 R11: 0000000000000246 R12: 00000000006dbc20
R13: 0000000000000000 R14: 000000000000002d R15: 20c49ba5e353f7cf
Kernel Offset: disabled
Rebooting in 86400 seconds..


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