On Mon, Jul 09, 2012 at 03:31:42PM +0100, Ben Hutchings wrote:
> 3.2-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Jan Kara <j...@suse.cz>
>
> commit adee11b2085bee90bd8f4f52123ffb07882d6256 upstream.
>
> Check provided length of partition table so that (possibly maliciously)
> corrupted partition table cannot cause accessing data beyond current buffer.
>
> Signed-off-by: Jan Kara <j...@suse.cz>
> Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
> ---
> fs/udf/super.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/udf/super.c b/fs/udf/super.c
> index 9da6f4e..ce911f5 100644
> --- a/fs/udf/super.c
> +++ b/fs/udf/super.c
[...]
> @@ -1232,13 +1233,20 @@ static int udf_load_logicalvol(struct super_block
> *sb, sector_t block,
> return 1;
> BUG_ON(ident != TAG_IDENT_LVD);
> lvd = (struct logicalVolDesc *)bh->b_data;
> + table_len = le32_to_cpu(lvd->mapTableLength);
> + if (sizeof(*lvd) + table_len > sb->s_blocksize) {
[...]
I don't think this is sufficient, unless there has been some prior
validation of lvd->mapTableLength. On a 32-bit machine, the addition
may overflow. The untrusted value has to be validated before doing
any arithmetic on it, e.g.:
if (table_len > sb->s_blocksize - sizeof(*lv)) {
Ben.
--
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
- Albert Camus
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