[syzbot] [f2fs?] KASAN: null-ptr-deref Write in f2fs_stop_gc_thread

[syzbot <syzbot+1a8e2b31f2ac9bd3d148@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    2c9b3512402e Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=158ef15e980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f4925140c45a2a50
dashboard link: https://syzkaller.appspot.com/bug?extid=1a8e2b31f2ac9bd3d148
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136eee95980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1510b445980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3c29a41eae6b/disk-2c9b3512.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/938da4f6bc30/vmlinux-2c9b3512.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4f9521f6c1ef/bzImage-2c9b3512.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/1d96e2146be6/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/f1a30c7339a7/mount_14.gz
mounted in repro #3: https://storage.googleapis.com/syzbot-assets/b4ae6212a921/mount_18.gz

The issue was bisected to:

commit 3bdb7f161697e2d5123b89fe1778ef17a44858e7
Author: Jaegeuk Kim <jaegeuk@kernel.org>
Date:   Wed Apr 3 23:07:53 2024 +0000

    f2fs: don't set RO when shutting down f2fs

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15dcb445980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=17dcb445980000
console output: https://syzkaller.appspot.com/x/log.txt?x=13dcb445980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1a8e2b31f2ac9bd3d148@syzkaller.appspotmail.com
Fixes: 3bdb7f161697 ("f2fs: don't set RO when shutting down f2fs")

F2FS-fs (loop4): Mounted with checkpoint version = 48b305e5
F2FS-fs (loop4): Stopped filesystem due to reason: 0
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline]
BUG: KASAN: null-ptr-deref in __refcount_add include/linux/refcount.h:184 [inline]
BUG: KASAN: null-ptr-deref in __refcount_inc include/linux/refcount.h:241 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:258 [inline]
BUG: KASAN: null-ptr-deref in get_task_struct include/linux/sched/task.h:118 [inline]
BUG: KASAN: null-ptr-deref in kthread_stop+0xca/0x630 kernel/kthread.c:704
Write of size 4 at addr 0000000000000028 by task syz-executor169/7772

CPU: 1 PID: 7772 Comm: syz-executor169 Not tainted 6.10.0-syzkaller-11185-g2c9b3512402e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_report+0xe8/0x550 mm/kasan/report.c:491
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline]
 __refcount_add include/linux/refcount.h:184 [inline]
 __refcount_inc include/linux/refcount.h:241 [inline]
 refcount_inc include/linux/refcount.h:258 [inline]
 get_task_struct include/linux/sched/task.h:118 [inline]
 kthread_stop+0xca/0x630 kernel/kthread.c:704
 f2fs_stop_gc_thread+0x65/0xb0 fs/f2fs/gc.c:210
 f2fs_do_shutdown+0x192/0x540 fs/f2fs/file.c:2283
 f2fs_ioc_shutdown fs/f2fs/file.c:2325 [inline]
 __f2fs_ioctl+0x443a/0xbe60 fs/f2fs/file.c:4325
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fac5a221249
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 1d 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:00007fac5a1ce218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fac5a2a8708 RCX: 00007fac5a221249
RDX: 0000000020000140 RSI: 000000008004587d RDI: 0000000000000005
RBP: 00007fac5a2a8700 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fac5a274b1c
R13: 00007fac5a274040 R14: 00007fac5a26e057 R15: 8c02ea27aa268e19
 </TASK>
==================================================================


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