[U-Boot] [PATCH] FAT: buffer overflow with FAT12/16
Mikhail Zolotaryov
lebon at lebon.org.ua
Wed Oct 20 09:23:51 CEST 2010
Stefano,
you're right, sorry for that. Isn't it better to define LINEAR_PREFETCH_SIZE as
2 (blocks) and change get_vfatname() to something like that in such case:
__u8 *buflimit = cluster + ((curclust == 0) ?
LINEAR_PREFETCH_SIZE :
mydata->clust_size
) * SECTOR_SIZE;
Regards,
Mikhail
On 20.10.10 09:51, Stefano Babic wrote:
> Last commit 3831530dcb7b71329c272ccd6181f8038b6a6dd0a was intended
> "explicitly specify FAT12/16 root directory parsing buffer size, instead
> of relying on cluster size". Howver, the underlying function requires
> the size of the buffer in blocks, not in bytes, and instead of passing
> a double sector size a request for 1024 blocks is sent. This generates
> a buffer overflow with overwriting of other structure (in the case seen,
> USB structures were overwritten).
>
> Signed-off-by: Stefano Babic <sbabic at denx.de>
> CC: Mikhail Zolotaryov <lebon at lebon.org.ua>
>
> ---
> fs/fat/fat.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/fat/fat.c b/fs/fat/fat.c
> index 744e961..a75e4f2 100644
> --- a/fs/fat/fat.c
> +++ b/fs/fat/fat.c
> @@ -858,7 +858,7 @@ do_fat_read (const char *filename, void *buffer, unsigned long maxsize,
> if (disk_read(cursect,
> (mydata->fatsize == 32) ?
> (mydata->clust_size) :
> - LINEAR_PREFETCH_SIZE,
> + LINEAR_PREFETCH_SIZE / SECTOR_SIZE,
> do_fat_read_block) < 0) {
> debug("Error: reading rootdir block\n");
> return -1;
More information about the U-Boot
mailing list