[syzbot] [ntfs3?] KMSAN: uninit-value in attr_set_size

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9b0d551bcc05 Merge tag 'pull-misc' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11da692f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=50fb29d81ff5a3df
dashboard link: https://syzkaller.appspot.com/bug?extid=83c9dd5c0dcf6184fdbf
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=143915cd980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13dbd334580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/90b0fb888152/disk-9b0d551b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1120c646f284/vmlinux-9b0d551b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/df9bbfa8cbe6/bzImage-9b0d551b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/0277c876bf11/mount_8.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+83c9dd...@syzkaller.appspotmail.com

ntfs3(loop0): Failed to initialize $Extend.
=====================================================
BUG: KMSAN: uninit-value in attr_set_size+0x471b/0x6740 fs/ntfs3/attrib.c:653
attr_set_size+0x471b/0x6740 fs/ntfs3/attrib.c:653
ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
do_splice_from fs/splice.c:938 [inline]
direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0x1e0/0x350 fs/splice.c:1230
do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
__x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
attr_set_size+0x4714/0x6740 fs/ntfs3/attrib.c:655
ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
do_splice_from fs/splice.c:938 [inline]
direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0x1e0/0x350 fs/splice.c:1230
do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
__x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
ni_create_attr_list+0x1b9b/0x1db0 fs/ntfs3/frecord.c:872
attr_set_size+0x4174/0x6740 fs/ntfs3/attrib.c:640
ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
do_splice_from fs/splice.c:938 [inline]
direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0x1e0/0x350 fs/splice.c:1230
do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
__x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5245 [inline]
__do_kmalloc_node mm/slub.c:5602 [inline]
__kmalloc_noprof+0xabb/0x1b40 mm/slub.c:5615
kmalloc_noprof include/linux/slab.h:961 [inline]
ni_create_attr_list+0x1ca/0x1db0 fs/ntfs3/frecord.c:770
attr_set_size+0x4174/0x6740 fs/ntfs3/attrib.c:640
ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
do_splice_from fs/splice.c:938 [inline]
direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0x1e0/0x350 fs/splice.c:1230
do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
__x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 6199 Comm: syz.0.54 Not tainted syzkaller #0 PREEMPT(none)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
=====================================================


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