linux-kernel - Re: [syzbot] [jfs?] stack segment fault in dbUpdatePMap

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Message-ID: <69065909.050a0220.29fc44.000a.GAE@google.com>
Date: Sat, 01 Nov 2025 12:01:29 -0700
From: syzbot <syzbot+f5a5b157b7336d1fda1d@...kaller.appspotmail.com>
To: jfs-discussion@...ts.sourceforge.net, linux-kernel@...r.kernel.org, 
	shaggy@...nel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [jfs?] stack segment fault in dbUpdatePMap

syzbot has found a reproducer for the following issue on:

HEAD commit:    ba36dd5ee6fd Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16032342580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=41ad820f608cb833
dashboard link: https://syzkaller.appspot.com/bug?extid=f5a5b157b7336d1fda1d
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1760b932580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16ca3258580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b151a6a8b947/disk-ba36dd5e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ddc072fd4513/vmlinux-ba36dd5e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7cdcc5b6e230/bzImage-ba36dd5e.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d873406bb3bb/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=113b4292580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f5a5b157b7336d1fda1d@...kaller.appspotmail.com

Oops: stack segment: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 122 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__list_add_valid_or_report+0x3e/0x130 lib/list_debug.c:29
Code: 00 00 00 48 89 d3 48 85 d2 0f 84 93 00 00 00 49 89 f6 49 89 ff 49 bd 00 00 00 00 00 fc ff df 4c 8d 63 08 4c 89 e5 48 c1 ed 03 <42> 80 7c 2d 00 00 74 08 4c 89 e7 e8 32 c4 9d fd 4d 39 34 24 75 71
RSP: 0018:ffffc900039e7a20 EFLAGS: 00010a06
RAX: 0000000000000000 RBX: dead000000000100 RCX: ffff88801ff1bc00
RDX: dead000000000100 RSI: ffffc90003229330 RDI: ffff88814729dc40
RBP: 1bd5a00000000021 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1dac5cf R12: dead000000000108
R13: dffffc0000000000 R14: ffffc90003229330 R15: ffff88814729dc40
FS:  0000000000000000(0000) GS:ffff888126ef9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffcb89299c CR3: 0000000035922000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __list_add_valid include/linux/list.h:96 [inline]
 __list_add include/linux/list.h:158 [inline]
 list_add include/linux/list.h:177 [inline]
 dbUpdatePMap+0x7e4/0xeb0 fs/jfs/jfs_dmap.c:577
 txAllocPMap+0x57d/0x6b0 fs/jfs/jfs_txnmgr.c:2426
 txUpdateMap+0x2a2/0x9c0 fs/jfs/jfs_txnmgr.c:2309
 txLazyCommit fs/jfs/jfs_txnmgr.c:2665 [inline]
 jfs_lazycommit+0x3f1/0xa10 fs/jfs/jfs_txnmgr.c:2734
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 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:__list_add_valid_or_report+0x3e/0x130 lib/list_debug.c:29
Code: 00 00 00 48 89 d3 48 85 d2 0f 84 93 00 00 00 49 89 f6 49 89 ff 49 bd 00 00 00 00 00 fc ff df 4c 8d 63 08 4c 89 e5 48 c1 ed 03 <42> 80 7c 2d 00 00 74 08 4c 89 e7 e8 32 c4 9d fd 4d 39 34 24 75 71
RSP: 0018:ffffc900039e7a20 EFLAGS: 00010a06
RAX: 0000000000000000 RBX: dead000000000100 RCX: ffff88801ff1bc00
RDX: dead000000000100 RSI: ffffc90003229330 RDI: ffff88814729dc40
RBP: 1bd5a00000000021 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1dac5cf R12: dead000000000108
R13: dffffc0000000000 R14: ffffc90003229330 R15: ffff88814729dc40
FS:  0000000000000000(0000) GS:ffff888126ef9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffcb89299c CR3: 0000000035922000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 48 89             	add    %cl,-0x77(%rax)
   5:	d3 48 85             	rorl   %cl,-0x7b(%rax)
   8:	d2 0f                	rorb   %cl,(%rdi)
   a:	84 93 00 00 00 49    	test   %dl,0x49000000(%rbx)
  10:	89 f6                	mov    %esi,%esi
  12:	49 89 ff             	mov    %rdi,%r15
  15:	49 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%r13
  1c:	fc ff df
  1f:	4c 8d 63 08          	lea    0x8(%rbx),%r12
  23:	4c 89 e5             	mov    %r12,%rbp
  26:	48 c1 ed 03          	shr    $0x3,%rbp
* 2a:	42 80 7c 2d 00 00    	cmpb   $0x0,0x0(%rbp,%r13,1) <-- trapping instruction
  30:	74 08                	je     0x3a
  32:	4c 89 e7             	mov    %r12,%rdi
  35:	e8 32 c4 9d fd       	call   0xfd9dc46c
  3a:	4d 39 34 24          	cmp    %r14,(%r12)
  3e:	75 71                	jne    0xb1


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.