Re: [syzbot] [f2fs?] general protection fault in f2fs_in_warm_node_list

[syzbot <syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in f2fs_in_warm_node_list

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:NODE_MAPPING fs/f2fs/f2fs.h:2260 [inline]
RIP: 0010:is_node_folio fs/f2fs/f2fs.h:2270 [inline]
RIP: 0010:f2fs_in_warm_node_list+0xbd/0x290 fs/f2fs/node.c:330
Code: 00 00 4d 03 3c 24 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 71 a9 fd fd 4d 8b 3f 49 83 c7 30 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 54 a9 fd fd 4d 3b 37 74 19 e8 da
RSP: 0018:ffffc900001479a8 EFLAGS: 00010206
RAX: 0000000000000006 RBX: ffffea0000aa0c80 RCX: ffff88801c6e9e80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: dffffc0000000000 R08: ffffffff8f6a32b7 R09: 1ffffffff1ed4656
R10: dffffc0000000000 R11: fffffbfff1ed4657 R12: ffff8880394a8798
R13: dffffc0000000000 R14: ffff88805c522950 R15: 0000000000000030
FS:  0000000000000000(0000) GS:ffff888126340000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd37652e50 CR3: 0000000044d76000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 f2fs_write_end_io+0x691/0x1020 fs/f2fs/data.c:400
 blk_update_request+0x57e/0xe60 block/blk-mq.c:1016
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1178
 blk_flush_complete_seq+0x687/0xce0 block/blk-flush.c:191
 flush_end_io+0xc40/0xf30 block/blk-flush.c:251
 __blk_mq_end_request+0x4a9/0x680 block/blk-mq.c:1168
 blk_complete_reqs block/blk-mq.c:1253 [inline]
 blk_done_softirq+0x10a/0x160 block/blk-mq.c:1258
 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622
 run_ksoftirqd+0x52/0x180 kernel/softirq.c:1063
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:NODE_MAPPING fs/f2fs/f2fs.h:2260 [inline]
RIP: 0010:is_node_folio fs/f2fs/f2fs.h:2270 [inline]
RIP: 0010:f2fs_in_warm_node_list+0xbd/0x290 fs/f2fs/node.c:330
Code: 00 00 4d 03 3c 24 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 71 a9 fd fd 4d 8b 3f 49 83 c7 30 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 54 a9 fd fd 4d 3b 37 74 19 e8 da
RSP: 0018:ffffc900001479a8 EFLAGS: 00010206
RAX: 0000000000000006 RBX: ffffea0000aa0c80 RCX: ffff88801c6e9e80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: dffffc0000000000 R08: ffffffff8f6a32b7 R09: 1ffffffff1ed4656
R10: dffffc0000000000 R11: fffffbfff1ed4657 R12: ffff8880394a8798
R13: dffffc0000000000 R14: ffff88805c522950 R15: 0000000000000030
FS:  0000000000000000(0000) GS:ffff888126340000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd37652e50 CR3: 0000000044d76000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	4d 03 3c 24          	add    (%r12),%r15
   6:	4c 89 f8             	mov    %r15,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
  12:	74 08                	je     0x1c
  14:	4c 89 ff             	mov    %r15,%rdi
  17:	e8 71 a9 fd fd       	call   0xfdfda98d
  1c:	4d 8b 3f             	mov    (%r15),%r15
  1f:	49 83 c7 30          	add    $0x30,%r15
  23:	4c 89 f8             	mov    %r15,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ff             	mov    %r15,%rdi
  34:	e8 54 a9 fd fd       	call   0xfdfda98d
  39:	4d 3b 37             	cmp    (%r15),%r14
  3c:	74 19                	je     0x57
  3e:	e8                   	.byte 0xe8
  3f:	da                   	.byte 0xda


Tested on:

commit:         af4e9ef3 uaccess: Fix scoped_user_read_access() for 'p..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=129818d6580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2a019678b1a3a692
dashboard link: https://syzkaller.appspot.com/bug?extid=6e4cb1cac5efc96ea0ca
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11948d5a580000