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

syzbot
2026-01-22T18:49:41Z

Hello,

syzbot found the following issue on:

HEAD commit: e84d960149e7 Merge tag 'for-6.19-rc5-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16784b9a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=46b5f80a6e7aaa5c
dashboard link: https://syzkaller.appspot.com/bug?extid=d3a57c32b9112d7b01ec
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=158fdb9a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=170153fa580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2d9623942f5a/disk-e84d9601.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/61b0e15f8560/vmlinux-e84d9601.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8b71c88680c4/bzImage-e84d9601.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/7023ce628e6e/mount_2.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=130153fa580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3a57c32b9112d7b01ec@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in txLock+0x13a2/0x2900 fs/jfs/jfs_txnmgr.c:659
txLock+0x13a2/0x2900 fs/jfs/jfs_txnmgr.c:659
xtTruncate+0x1002/0x5050 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+0x999/0x1050 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+0xbe2/0x15d0 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+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
__alloc_frozen_pages_noprof+0x421/0xab0 mm/page_alloc.c:5263
alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2486
alloc_frozen_pages_noprof mm/mempolicy.c:2557 [inline]
alloc_pages_noprof+0x102/0x280 mm/mempolicy.c:2577
vm_area_alloc_pages mm/vmalloc.c:3649 [inline]
__vmalloc_area_node mm/vmalloc.c:3863 [inline]
__vmalloc_node_range_noprof+0xa94/0x2d90 mm/vmalloc.c:4051
__vmalloc_node_noprof mm/vmalloc.c:4111 [inline]
vmalloc_noprof+0xce/0x140 mm/vmalloc.c:4146
txInit+0xb5c/0xfa0 fs/jfs/jfs_txnmgr.c:297
init_jfs_fs+0x1b2/0xcb0 fs/jfs/super.c:977
do_one_initcall+0x22b/0xad0 init/main.c:1378
do_initcall_level+0x157/0x2e0 init/main.c:1440
do_initcalls+0x176/0x310 init/main.c:1456
do_basic_setup+0x1d/0x30 init/main.c:1475
kernel_init_freeable+0x214/0x430 init/main.c:1688
kernel_init+0x2f/0x5e0 init/main.c:1578
ret_from_fork+0x208/0x710 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

CPU: 1 UID: 0 PID: 6025 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
=====================================================

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