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ntfs3: reject inodes with zero non-DOS link count

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ntfs_read_mft() counts file name attributes into two variables:
names (all names including DOS 8.3) and links (non-DOS names
only). The validation at line 424 checks names but set_nlink()
at line 436 uses links. A corrupted NTFS image where all file
name attributes have type FILE_NAME_DOS passes the names check
but results in set_nlink(inode, 0).

When such an inode is loaded via a code path that passes name=NULL
to ntfs_iget5() and the nlink=0 inode enters the VFS. The subsequent
unlink, rmdir, or rename targeting this inode calls drop_nlink()
which triggers WARN_ON(inode->i_nlink == 0) in fs/inode.c.

An all-DOS-name MFT record cannot exist on a valid NTFS volume.
Reject such records by checking for links == 0 before
calling set_nlink().

Signed-off-by: Ziyi Guo <n7l8m4@u.northwestern.edu>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
This commit is contained in:
Ziyi Guo 2026-02-10 15:56:34 +00:00 committed by Konstantin Komarov
parent 6de23f81a5
commit e10e72f697
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1 changed files with 5 additions and 0 deletions
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fs/ntfs3/inode.c
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@ -432,6 +432,11 @@ static struct inode *ntfs_read_mft(struct inode *inode,
ni->mi.dirty = true;
}
if (!links) {
err = -EINVAL;
goto out;
}
set_nlink(inode, links);
if (S_ISDIR(mode)) {