[v6.1] BUG: unable to handle kernel NULL pointer dereference in nilfs_segctor_do_construct

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bf4ad6fa4e53 Linux 6.1.28
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11113226280000
kernel config: https://syzkaller.appspot.com/x/.config?x=26fca33e75c97e43
dashboard link: https://syzkaller.appspot.com/bug?extid=d75a90893a2e369c2be6
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/058ee41df9de/disk-bf4ad6fa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/480706160d27/vmlinux-bf4ad6fa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e6a9f4f20a23/bzImage-bf4ad6fa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d75a90...@syzkaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 2780f067 P4D 2780f067 PUD 3a940067 PMD 0
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 19561 Comm: syz-executor.2 Not tainted 6.1.28-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc90003646ff8 EFLAGS: 00010246
RAX: 0000000000000020 RBX: 0000000000000000 RCX: ffffffff8b28cfe0
RDX: ffffc90003647360 RSI: ffffc90003647340 RDI: ffff888073b6e000
RBP: ffffc90003647530 R08: ffffffff834b8f0d R09: ffffed1010f50b4c
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920006c8e70
R13: dffffc0000000000 R14: ffffc90003647301 R15: 0000000000000001
FS: 00007feec51c0700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000751c4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
nilfs_segctor_assign fs/nilfs2/segment.c:1649 [inline]
nilfs_segctor_do_construct+0x3993/0x6cc0 fs/nilfs2/segment.c:2079
nilfs_construct_dsync_segment+0x5c0/0x6c0 fs/nilfs2/segment.c:2333
nilfs_sync_file+0xb8/0x260 fs/nilfs2/file.c:32
generic_write_sync include/linux/fs.h:2897 [inline]
generic_file_write_iter+0x29d/0x310 mm/filemap.c:3918
do_iter_write+0x6e6/0xc50 fs/read_write.c:861
iter_file_splice_write+0x806/0xfa0 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0xe3/0x1c0 fs/splice.c:931
splice_direct_to_actor+0x4c0/0xbd0 fs/splice.c:886
do_splice_direct+0x27f/0x3c0 fs/splice.c:974
do_sendfile+0x61c/0xff0 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7feec448c169
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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:00007feec51c0168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007feec45abf80 RCX: 00007feec448c169
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007feec44e7ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd48e10f4f R14: 00007feec51c0300 R15: 0000000000022000
</TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc90003646ff8 EFLAGS: 00010246
RAX: 0000000000000020 RBX: 0000000000000000 RCX: ffffffff8b28cfe0
RDX: ffffc90003647360 RSI: ffffc90003647340 RDI: ffff888073b6e000
RBP: ffffc90003647530 R08: ffffffff834b8f0d R09: ffffed1010f50b4c
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920006c8e70
R13: dffffc0000000000 R14: ffffc90003647301 R15: 0000000000000001
FS: 00007feec51c0700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000751c4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.