linux-kernel - [syzbot] BUG: unable to handle kernel NULL pointer dereference in get_next_nat

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Message-ID: <00000000000039f36005eb3649ab@google.com>
Date:   Mon, 17 Oct 2022 00:54:32 -0700
From:   syzbot <syzbot+f3829d0d4cd1c750c0c1@...kaller.appspotmail.com>
To:     chao@...nel.org, jaegeuk@...nel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] BUG: unable to handle kernel NULL pointer dereference in
 get_next_nat_page (2)

Hello,

syzbot found the following issue on:

HEAD commit:    493ffd6605b2 Merge tag 'ucount-rlimits-cleanups-for-v5.19'..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17cbb31a880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d19f5d16783f901
dashboard link: https://syzkaller.appspot.com/bug?extid=f3829d0d4cd1c750c0c1
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, 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/f1ff6481e26f/disk-493ffd66.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/101bd3c7ae47/vmlinux-493ffd66.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f3829d0d4cd1c750c0c1@...kaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 7991b067 P4D 7991b067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3644 Comm: syz-executor.4 Not tainted 6.0.0-syzkaller-09423-g493ffd6605b2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:ffffc900042df7e0 EFLAGS: 00010292
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888027258000
RDX: 0000000000000000 RSI: ffffea0002495640 RDI: ffff88806f559e38
RBP: ffffea0002469d00 R08: ffffffff81b5b45b R09: fffff94000492ac9
R10: fffff94000492ac9 R11: 1ffffd4000492ac8 R12: ffffea0002469d00
R13: dffffc0000000000 R14: ffffea0002495640 R15: ffffea0002469d08
FS:  0000555555873400(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000035168000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 get_next_nat_page+0x3a9/0x770 fs/f2fs/node.c:154
 __flush_nat_entry_set fs/f2fs/node.c:3005 [inline]
 f2fs_flush_nat_entries+0x9e3/0x1bf0 fs/f2fs/node.c:3109
 f2fs_write_checkpoint+0x14f1/0x1d70 fs/f2fs/checkpoint.c:1667
 kill_f2fs_super+0x22e/0x3c0 fs/f2fs/super.c:4538
 deactivate_locked_super+0xa7/0xf0 fs/super.c:331
 cleanup_mnt+0x4ce/0x560 fs/namespace.c:1186
 task_work_run+0x146/0x1c0 kernel/task_work.c:177
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x150 kernel/entry/common.c:169
 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:294
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f1023c8ca17
Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 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:00007ffd840e9448 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f1023c8ca17
RDX: 00007ffd840e951b RSI: 000000000000000a RDI: 00007ffd840e9510
RBP: 00007ffd840e9510 R08: 00000000ffffffff R09: 00007ffd840e92e0
R10: 00005555558748b3 R11: 0000000000000246 R12: 00007f1023ce55f6
R13: 00007ffd840ea5d0 R14: 0000555555874810 R15: 00007ffd840ea610
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:ffffc900042df7e0 EFLAGS: 00010292
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888027258000
RDX: 0000000000000000 RSI: ffffea0002495640 RDI: ffff88806f559e38
RBP: ffffea0002469d00 R08: ffffffff81b5b45b R09: fffff94000492ac9
R10: fffff94000492ac9 R11: 1ffffd4000492ac8 R12: ffffea0002469d00
R13: dffffc0000000000 R14: ffffea0002495640 R15: ffffea0002469d08
FS:  0000555555873400(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000035168000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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