On Fri, Nov 18, 2016 at 01:38:39PM -0500, Theodore Ts'o wrote:
> @@ -3567,7 +3567,15 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> if (blocksize < EXT4_MIN_BLOCK_SIZE ||
> blocksize > EXT4_MAX_BLOCK_SIZE) {
> ext4_msg(sb, KERN_ERR,
> - "Unsupported filesystem blocksize %d", blocksize);
> + "Unsupported filesystem blocksize %d (%d log_block_size)",
> + blocksize, le32_to_cpu(es->s_log_block_size));
> + goto failed_mount;
> + }
> + if (le32_to_cpu(es->s_log_block_size) >
> + (EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
> + ext4_msg(sb, KERN_ERR,
> + "Invalid log block size: %u",
> + le32_to_cpu(es->s_log_block_size));
> goto failed_mount;
> }
>
This isn't validating s_log_block_size until after it's already been used in a
shift, which means the code can have undefined behavior (shift by a value too
large). Would it make sense to do something like the following instead?
Similarly for the cluster size case.
blocksize =
BLOCK_SIZE << min_t(u32, le32_to_cpu(es->s_log_block_size), 20);
if (blocksize < EXT4_MIN_BLOCK_SIZE ||
blocksize > EXT4_MAX_BLOCK_SIZE) {
ext4_msg(sb, KERN_ERR,
"Unsupported filesystem blocksize %d (%u bits)",
blocksize, le32_to_cpu(es->s_log_block_size));
goto failed_mount;
}
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