kernel BUG in mod_timer

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 41f36d7859a7 Linux 4.14.296
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1770c146880000
kernel config: https://syzkaller.appspot.com/x/.config?x=20cc5ea0fe276fa6
dashboard link: https://syzkaller.appspot.com/bug?extid=db882eff0b24c7941918
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/941b591cedec/disk-41f36d78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2eea2720f8fc/vmlinux-41f36d78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c3ce0be6b9a/bzImage-41f36d78.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+db882e...@syzkaller.appspotmail.com

Remounting filesystem read-only
Remounting filesystem read-only
NILFS (loop2): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds
NILFS (loop2): mounting fs with errors
------------[ cut here ]------------
kernel BUG at kernel/time/timer.c:939!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 9568 Comm: syz-executor.3 Not tainted 4.14.296-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
task: ffff8880b3aea140 task.stack: ffff88805ec30000
RIP: 0010:__mod_timer kernel/time/timer.c:939 [inline]
RIP: 0010:mod_timer+0x7fd/0xf70 kernel/time/timer.c:1070
RSP: 0018:ffff88805ec37b48 EFLAGS: 00010246
RAX: 0000000000040000 RBX: 00000000ffffe903 RCX: ffffc90007e1d000
RDX: 0000000000040000 RSI: ffffffff81489b4d RDI: ffff8880aadcfdb0
RBP: ffff8880aadcfd98 R08: ffff8880aadcfc80 R09: 0000000000040657
R10: ffff8880b3aeaa68 R11: ffff8880b3aea140 R12: dffffc0000000000
R13: 1ffff1100bd86f71 R14: ffff8880aadcfb00 R15: ffff88805ec37c8a
FS: 00007f3185b53700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ea28000 CR3: 00000000ae6b7000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
nilfs_segctor_start_timer fs/nilfs2/segment.c:2139 [inline]
nilfs_transaction_commit+0x6b4/0xae0 fs/nilfs2/segment.c:288
nilfs_evict_inode+0x2be/0x3a0 fs/nilfs2/inode.c:967
evict+0x2c8/0x700 fs/inode.c:554
iput_final fs/inode.c:1523 [inline]
iput+0x458/0x7e0 fs/inode.c:1550
dentry_unlink_inode+0x25c/0x310 fs/dcache.c:387
d_delete+0x1c5/0x280 fs/dcache.c:2417
vfs_rmdir.part.0+0x260/0x390 fs/namei.c:3922
vfs_rmdir fs/namei.c:3895 [inline]
do_rmdir+0x334/0x3c0 fs/namei.c:3970
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f31875e05a9
RSP: 002b:00007f3185b53168 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f3187700f80 RCX: 00007f31875e05a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000040
RBP: 00007f318763b7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc9302446f R14: 00007f3185b53300 R15: 0000000000022000
Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 66 06 00 00 48 89 5d 10 4c 89 64 24 10 c7 44 24 08 01 00 00 00 e9 db fc ff ff e8 73 ac 0c 00 <0f> 0b e8 6c ac 0c 00 8b 5c 24 0c 48 b8 00 00 00 00 00 fc ff df
RIP: __mod_timer kernel/time/timer.c:939 [inline] RSP: ffff88805ec37b48
RIP: mod_timer+0x7fd/0xf70 kernel/time/timer.c:1070 RSP: ffff88805ec37b48
---[ end trace 39bf8db1c45212e0 ]---


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 41f36d7859a7 Linux 4.14.296
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=1537c391880000

kernel config: https://syzkaller.appspot.com/x/.config?x=20cc5ea0fe276fa6
dashboard link: https://syzkaller.appspot.com/bug?extid=db882eff0b24c7941918
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14fac051880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=162fbc89880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/941b591cedec/disk-41f36d78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2eea2720f8fc/vmlinux-41f36d78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c3ce0be6b9a/bzImage-41f36d78.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/9f44fd0203cc/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+db882e...@syzkaller.appspotmail.com

NILFS (loop5): mounting fs with errors
NILFS (loop3): mounting fs with errors
NILFS (loop5): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds
NILFS (loop3): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds

------------[ cut here ]------------
kernel BUG at kernel/time/timer.c:939!

Remounting filesystem read-only

invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:

CPU: 0 PID: 8031 Comm: syz-executor706 Not tainted 4.14.296-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022

task: ffff8880b2908640 task.stack: ffff8880b32a8000

RIP: 0010:__mod_timer kernel/time/timer.c:939 [inline]
RIP: 0010:mod_timer+0x7fd/0xf70 kernel/time/timer.c:1070

RSP: 0018:ffff8880b32afb48 EFLAGS: 00010297
RAX: ffff8880b2908640 RBX: 00000000ffff99e6 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 00000000ffff99e6 RDI: ffff8880b1928bf0
RBP: ffff8880b1928bd8 R08: ffff8880b1928ac0 R09: 000000000004058d
R10: ffff8880b2908f68 R11: ffff8880b2908640 R12: dffffc0000000000
R13: 1ffff11016655f71 R14: ffff8880b1928940 R15: ffff8880b32afc8a
FS: 00007f450d3d4700(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000555555bd8628 CR3: 00000000a04a7000 CR4: 00000000003406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

NILFS (loop4): error -4 creating segctord thread

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:

NILFS (loop2): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds

nilfs_segctor_start_timer fs/nilfs2/segment.c:2139 [inline]
nilfs_transaction_commit+0x6b4/0xae0 fs/nilfs2/segment.c:288
nilfs_evict_inode+0x2be/0x3a0 fs/nilfs2/inode.c:967

NILFS (loop2): mounting fs with errors

evict+0x2c8/0x700 fs/inode.c:554
iput_final fs/inode.c:1523 [inline]
iput+0x458/0x7e0 fs/inode.c:1550
dentry_unlink_inode+0x25c/0x310 fs/dcache.c:387
d_delete+0x1c5/0x280 fs/dcache.c:2417
vfs_rmdir.part.0+0x260/0x390 fs/namei.c:3922
vfs_rmdir fs/namei.c:3895 [inline]
do_rmdir+0x334/0x3c0 fs/namei.c:3970
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

RIP: 0033:0x7f450d44a199
RSP: 002b:00007f450d3d42f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f450d4d14b0 RCX: 00007f450d44a199
RDX: 00007f450d3d4700 RSI: d1cff92d779b1a2f RDI: 0000000020000040
RBP: 00007f450d49c730 R08: 00007f450d3d4700 R09: 0000000000000000
R10: 00007f450d3d4700 R11: 0000000000000246 R12: 00007f450d49c308
R13: 00007f450d49c0c8 R14: 0030656c69662f2e R15: 00007f450d4d14b8

Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 66 06 00 00 48 89 5d 10 4c 89 64 24 10 c7 44 24 08 01 00 00 00 e9 db fc ff ff e8 73 ac 0c 00 <0f> 0b e8 6c ac 0c 00 8b 5c 24 0c 48 b8 00 00 00 00 00 fc ff df

RIP: __mod_timer kernel/time/timer.c:939 [inline] RSP: ffff8880b32afb48
RIP: mod_timer+0x7fd/0xf70 kernel/time/timer.c:1070 RSP: ffff8880b32afb48
---[ end trace df24e578cdcca7e1 ]---