[syzbot] [ntfs3?] KMSAN: uninit-value in ntfs_iomap_begin (2)

[syzbot] [ntfs3?] KMSAN: uninit-value in ntfs_iomap_begin (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    962528fef902 Merge tag 'gpio-fixes-for-v7.2-rc1' of git://..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17b6af41580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f9f817cd15d2732a
dashboard link: https://syzkaller.appspot.com/bug?extid=4b4ec878e25fafefa70f
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7d3cfc78dc93/disk-962528fe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/17f3cac25390/vmlinux-962528fe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/80baf6bfce4e/bzImage-962528fe.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4b4ec878e25fafefa70f@syzkaller.appspotmail.com

loop1: detected capacity change from 0 to 4096
=====================================================
BUG: KMSAN: uninit-value in ntfs_iomap_begin+0x8a3/0x1550 fs/ntfs3/inode.c:781
 ntfs_iomap_begin+0x8a3/0x1550 fs/ntfs3/inode.c:781
 iomap_iter+0x9d9/0x14f0 fs/iomap/iter.c:110
 iomap_read_folio+0x67c/0xb20 fs/iomap/buffered-io.c:645
 ntfs_read_folio+0x74f/0x770 fs/ntfs3/inode.c:652
 filemap_read_folio mm/filemap.c:2510 [inline]
 do_read_cache_folio+0x96d/0x13d0 mm/filemap.c:4140
 do_read_cache_page mm/filemap.c:4206 [inline]
 read_cache_page+0x63/0x1e0 mm/filemap.c:4215
 read_mapping_page include/linux/pagemap.h:1009 [inline]
 inode_read_data+0xbb/0x560 fs/ntfs3/inode.c:1058
 ntfs_fill_super+0x720c/0x8820 fs/ntfs3/super.c:1582
 get_tree_bdev_flags+0x6ef/0x930 fs/super.c:1634
 get_tree_bdev+0x38/0x50 fs/super.c:1657
 ntfs_fs_get_tree+0x35/0x40 fs/ntfs3/super.c:1819
 vfs_get_tree+0xae/0x5d0 fs/super.c:1694
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x885/0x1dc0 fs/namespace.c:3841
 path_mount+0x7a2/0x20a0 fs/namespace.c:4161
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x704/0x7f0 fs/namespace.c:4367
 __x64_sys_mount+0xed/0x180 fs/namespace.c:4367
 x64_sys_call+0x39f0/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15d/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable lcn created at:
 ntfs_iomap_begin+0x157/0x1550 fs/ntfs3/inode.c:742
 iomap_iter+0x9d9/0x14f0 fs/iomap/iter.c:110

CPU: 0 UID: 0 PID: 5852 Comm: syz.1.9 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
=====================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup