linux-kernel - [syzbot] [bcachefs?] BUG: unable to handle kernel paging request in __bch2_bkey_unpack

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Message-ID: <6835d715.a70a0220.253bc2.00b9.GAE@google.com>
Date: Tue, 27 May 2025 08:15:33 -0700
From: syzbot <syzbot+9b7e20f8ff98aed7254e@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] BUG: unable to handle kernel paging request in __bch2_bkey_unpack_key

Hello,

syzbot found the following issue on:

HEAD commit:    ddddf9d64f73 Merge tag 'perf-core-2025-05-25' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=163e3170580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fd18a1001092f95b
dashboard link: https://syzkaller.appspot.com/bug?extid=9b7e20f8ff98aed7254e
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=160226d4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1465bdf4580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ddddf9d6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bc551d1d4e46/vmlinux-ddddf9d6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d26a6de23b0e/bzImage-ddddf9d6.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/92cf6b656172/mount_6.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b7e20f8ff98aed7254e@...kaller.appspotmail.com

BUG: unable to handle page fault for address: ffffed1108cc0204
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 5ffcd067 P4D 5ffcd067 PUD 0 
Oops: Oops: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5312 Comm: read_btree_node Not tainted 6.15.0-syzkaller-01599-gddddf9d64f73 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:unpack_state_init fs/bcachefs/bkey.c:151 [inline]
RIP: 0010:__bch2_bkey_unpack_key+0x5b/0xe10 fs/bcachefs/bkey.c:269
Code: 42 0f b6 04 38 84 c0 0f 85 b2 09 00 00 48 89 5c 24 18 0f b6 1b 8d 43 ff 4c 8d 34 c5 00 00 00 00 4d 01 ee 4c 89 f0 48 c1 e8 03 <42> 80 3c 38 00 74 08 4c 89 f7 e8 f6 32 0c fe 4c 89 74 24 08 49 8b
RSP: 0018:ffffc9000d336ab8 EFLAGS: 00010a02
RAX: 1ffff11108cc0204 RBX: 0000000000000000 RCX: ffff88801fd64880
RDX: 0000000000000000 RSI: ffff88803ed370c0 RDI: ffffc9000d336d30
RBP: ffffc9000d336dc8 R08: ffff88801fd64880 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc9000d336d30
R13: ffff888046601028 R14: ffff888846601020 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88808d6b1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed1108cc0204 CR3: 0000000043885000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __bch2_bkey_compat+0x4db/0xbd0 fs/bcachefs/bkey_methods.c:480
 bch2_bkey_compat fs/bcachefs/bkey_methods.h:134 [inline]
 validate_bset_keys+0x6c1/0x1390 fs/bcachefs/btree_io.c:983
 bch2_btree_node_read_done+0x18c8/0x4f60 fs/bcachefs/btree_io.c:1211
 btree_node_read_work+0x426/0xe30 fs/bcachefs/btree_io.c:1400
 bch2_btree_node_read+0x887/0x29f0 fs/bcachefs/btree_io.c:-1
 bch2_btree_node_fill+0xd12/0x14f0 fs/bcachefs/btree_cache.c:994
 bch2_btree_node_get_noiter+0xa2c/0x1000 fs/bcachefs/btree_cache.c:1261
 found_btree_node_is_readable fs/bcachefs/btree_node_scan.c:85 [inline]
 try_read_btree_node fs/bcachefs/btree_node_scan.c:220 [inline]
 read_btree_nodes_worker+0x1319/0x1e20 fs/bcachefs/btree_node_scan.c:269
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
CR2: ffffed1108cc0204
---[ end trace 0000000000000000 ]---
RIP: 0010:unpack_state_init fs/bcachefs/bkey.c:151 [inline]
RIP: 0010:__bch2_bkey_unpack_key+0x5b/0xe10 fs/bcachefs/bkey.c:269
Code: 42 0f b6 04 38 84 c0 0f 85 b2 09 00 00 48 89 5c 24 18 0f b6 1b 8d 43 ff 4c 8d 34 c5 00 00 00 00 4d 01 ee 4c 89 f0 48 c1 e8 03 <42> 80 3c 38 00 74 08 4c 89 f7 e8 f6 32 0c fe 4c 89 74 24 08 49 8b
RSP: 0018:ffffc9000d336ab8 EFLAGS: 00010a02
RAX: 1ffff11108cc0204 RBX: 0000000000000000 RCX: ffff88801fd64880
RDX: 0000000000000000 RSI: ffff88803ed370c0 RDI: ffffc9000d336d30
RBP: ffffc9000d336dc8 R08: ffff88801fd64880 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc9000d336d30
R13: ffff888046601028 R14: ffff888846601020 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88808d6b1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed1108cc0204 CR3: 0000000043885000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	42 0f b6 04 38       	movzbl (%rax,%r15,1),%eax
   5:	84 c0                	test   %al,%al
   7:	0f 85 b2 09 00 00    	jne    0x9bf
   d:	48 89 5c 24 18       	mov    %rbx,0x18(%rsp)
  12:	0f b6 1b             	movzbl (%rbx),%ebx
  15:	8d 43 ff             	lea    -0x1(%rbx),%eax
  18:	4c 8d 34 c5 00 00 00 	lea    0x0(,%rax,8),%r14
  1f:	00
  20:	4d 01 ee             	add    %r13,%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 f6 32 0c fe       	call   0xfe0c332f
  39:	4c 89 74 24 08       	mov    %r14,0x8(%rsp)
  3e:	49                   	rex.WB
  3f:	8b                   	.byte 0x8b


---
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