Re: [PATCH v2] vfat: don't read garbage after last dirent
From: OGAWA Hirofumi
Date: Mon Dec 24 2018 - 07:14:59 EST
Matteo Croce <mcroce@xxxxxxxxxx> writes:
> The FAT32 File System Specification states that:
> If DIR_Name == 0x00, then the directory entry is free, and there
> are no allocated directory entries after this one.
> The special 0 value, indicates to FAT file system driver code that
> the rest of the entries in this directory do not need to be examined
> because they are all free.
> This is not enforced by Linux, and is possible to read garbage if not
> all dirents after the last one are filled with zeroes.
>  http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/fatgen103.doc
> Reported-by: Timothy Redaelli <tredaelli@xxxxxxxxxx>
> Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
We have to handle all paths that is using fat_get_entry(), to make
With quick check, there are still several issues remaining. Please check
more. For example, looks like fat_parse_long()/fat_search_long() path is
missing, and fat_get_dotdot_entry(), fat_subdirs() too.
(while adding new entry, if we found zeroed entry, we would be better to
warn about fsck.)
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>