On Fri, Jul 11, 2008 at 02:19:06PM +0530, Manish Katiyar wrote:
> Below patch adds stricter checks in ext2fs_open() so that we catch bad
> block sizes earlier than later.
That concept seems fine; I'm curious why you found this necessary?
Did you have a corrupted filesystem where this caused major problems?
If so, can I have more details?
> fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
> - if (fs->blocksize == 0) {
> + if ((fs->blocksize < EXT2_MIN_BLOCK_SIZE) ||
> + (fs->blocksize > EXT2_MAX_BLOCK_SIZE) ||
> + (fs->blocksize % EXT2_MIN_BLOCK_SIZE != 0)) {
The first and last check is not necessary, given that EXT2_bLOCK_SIZE
is defined as:
#define EXT2_BLOCK_SIZE(s) (EXT2_MIN_BLOCK_SIZE << (s)->s_log_block_size)
So by definition, the blocksize will *always* be greater than or equal
to MIN_BLOCK_SIZE, and it always will be a multiple of EXT2_MIN_BLOCK_SIZE.
The more direct check which we could do would be something like this:
if ((fs->super->s_log_block_size < EXT2_MIN_BLOCK_LOG_SIZE) ||
(fs->super->s_log_block_size > EXT2_MAX_BLOCK_LOG_SIZE))
retval = EXT2_ET_CORRUPT_SUPERBLOCK;
goto cleanup;
}
... before setting fs->blocksize.
I'm curious what problem you were worried about that might happen if
fs->blocksize were greater than 64k, though.
- Ted
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