On Wed 13-05-15 11:56:46, Darrick J. Wong wrote:
> The journal revoke block recovery code does not check r_count for
> sanity, which means that an evil value of r_count could result in
> the kernel reading off the end of the revoke table and into whatever
> garbage lies beyond. This could crash the kernel, so fix that.
>
> However, in testing this fix, I discovered that the code to write
> out the revoke tables also was not correctly checking to see if the
> block was full -- the current offset check is fine so long as the
> revoke table space size is a multiple of the record size, but this
> is not true when either journal_csum_v[23] are set.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
...
> @@ -594,9 +594,14 @@ static void write_one_revoke_record(journal_t *journal,
> if (jbd2_journal_has_csum_v2or3(journal))
> csum_size = sizeof(struct jbd2_journal_revoke_tail);
>
> + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
> + sz = 8;
> + else
> + sz = 4;
> +
> /* Make sure we have a descriptor with space left for the record */
> if (descriptor) {
> - if (offset >= journal->j_blocksize - csum_size) {
> + if (offset + sz >= journal->j_blocksize - csum_size) {
Hum, but we can have strict inequality here, can't we? Otherwise the
patch looks good to me.
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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