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Phoronix0 Hot0 comments2 min read
Linux 7.3 Corrects Faulty Behavior Of FAT File-System Driver For Filenames Too Fat
The Linux msdos (FAT) filesystem driver contained a bug where msdos_format_name() failed to enforce an upper bound on filename length, silently truncating names longer than NAME_MAX (255 bytes) to the 8.3 format (11 bytes) while still reporting success. This let fat_scan() match against truncated names, causing open() calls on overly long path components to attach an inode to a dentry with an out-of-spec name, later triggering a WARN_ON_ONCE() in fanotify's event reporting path with an empty name reported to userspace. Huawei engineer Zizhi Wo identified and patched the issue by adding a length check at the single entry point for msdos name handling, aligning it with checks already performed by xfs, 9p, ceph, and simple_lookup(). Note vfat was unaffected since it already rejects overly long names via xlate_to_uni(). The fix has been merged for the upcoming Linux 7.3 kernel and is expected to be backported to stable kernels.
Source: https://www.phoronix.com/news/Linux-7.3-FAT. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.
