linux-kernel - Re: [syzbot] [jfs?] KMSAN: uninit-value in txLock

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Message-ID: <6973327a.a70a0220.35de72.0007.GAE@google.com>
Date: Fri, 23 Jan 2026 00:34:02 -0800
From: syzbot <syzbot+d3a57c32b9112d7b01ec@...kaller.appspotmail.com>
To: kartikey406@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [jfs?] KMSAN: uninit-value in txLock

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
kernel BUG in txLock

BUG at fs/jfs/jfs_txnmgr.c:662 assert(last)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_txnmgr.c:662!
Oops: invalid opcode: 0000 [#1] SMP PTI
CPU: 0 UID: 0 PID: 6674 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
RIP: 0010:txLock+0x144c/0x2900 fs/jfs/jfs_txnmgr.c:662
Code: c7 80 20 03 00 00 00 00 00 00 48 c7 c7 d5 c9 d1 91 48 c7 c6 76 86 aa 91 ba 96 02 00 00 48 c7 c1 b6 ff be 91 e8 d5 ae c7 fc 90 <0f> 0b 48 83 7d b8 00 0f 85 df 0f 00 00 4c 8b 6d 90 41 0f b7 5d 00
RSP: 0018:ffff888046c5b458 EFLAGS: 00010286
RAX: 000000000000002b RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffff888046c5b548 R08: ffffea000000000f R09: 0000000000000000
R10: ffff888237b1f028 R11: ffff88823f26ad60 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fb5748466c0(0000) GS:ffff8881aacec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000022000 CR3: 0000000049288000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 xtTruncate+0xffd/0x5210 fs/jfs/jfs_xtree.c:2337
 jfs_truncate_nolock+0x223/0x670 fs/jfs/inode.c:396
 jfs_truncate fs/jfs/inode.c:420 [inline]
 jfs_write_failed+0x207/0x3c0 fs/jfs/inode.c:295
 jfs_write_end+0xcc/0x110 fs/jfs/inode.c:322
 generic_perform_write+0x99f/0x1050 mm/filemap.c:4335
 __generic_file_write_iter+0x213/0x460 mm/filemap.c:4431
 generic_file_write_iter+0x131/0x980 mm/filemap.c:4457
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:686
 ksys_pwrite64 fs/read_write.c:793 [inline]
 __do_sys_pwrite64 fs/read_write.c:801 [inline]
 __se_sys_pwrite64 fs/read_write.c:798 [inline]
 __x64_sys_pwrite64+0x2ab/0x3b0 fs/read_write.c:798
 x64_sys_call+0xbaf/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:19
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb57399aef9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb574846028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fb573c05fa0 RCX: 00007fb57399aef9
RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007fb573a2fee0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb573c06038 R14: 00007fb573c05fa0 R15: 00007ffc81835368
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:txLock+0x144c/0x2900 fs/jfs/jfs_txnmgr.c:662
Code: c7 80 20 03 00 00 00 00 00 00 48 c7 c7 d5 c9 d1 91 48 c7 c6 76 86 aa 91 ba 96 02 00 00 48 c7 c1 b6 ff be 91 e8 d5 ae c7 fc 90 <0f> 0b 48 83 7d b8 00 0f 85 df 0f 00 00 4c 8b 6d 90 41 0f b7 5d 00
RSP: 0018:ffff888046c5b458 EFLAGS: 00010286
RAX: 000000000000002b RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffff888046c5b548 R08: ffffea000000000f R09: 0000000000000000
R10: ffff888237b1f028 R11: ffff88823f26ad60 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fb5748466c0(0000) GS:ffff8881aacec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000022000 CR3: 0000000049288000 CR4: 00000000003526f0


Tested on:

commit:         c072629f Merge tag 'v6.19-p4' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15128bfa580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=62c21fde37118981
dashboard link: https://syzkaller.appspot.com/bug?extid=d3a57c32b9112d7b01ec
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=17cf97fc580000