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Commit e703c206 authored by Lukas Czerner's avatar Lukas Czerner Committed by Jan Kara
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ext3: fix start and len arguments handling in ext3_trim_fs() 



The overflow might happen when passing blocknr into
ext3_get_group_no_and_offset(), because it expects type ext3_fsblk_t
which might be smaller than uint64_t. This will most likely happen when
calling FITRIM with the default argument len = ULLONG_MAX.

Fix this by using "end" variable instead of "start+len" as it is easier
to get right and specifically check that the end is not beyond the end
of the file system, so we are sure that the result of
get_group_no_and_offset() will not overflow. Otherwise truncate it to
the size of the file system.

Signed-off-by: default avatarLukas Czerner <lczerner@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent a0391a3a

fs/ext3/balloc.c

+39 −38
Original line number Diff line number Diff line
@@ -1973,7 +1973,7 @@ static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb, 
	sbi = EXT3_SB(sb);



	 /* Walk through the whole group */

	while (start < max) {

	while (start <= max) {

		start = bitmap_search_next_usable_block(start, bitmap_bh, max);

		if (start < 0)

			break;
@@ -1983,7 +1983,7 @@ static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb, 
		 * Allocate contiguous free extents by setting bits in the

		 * block bitmap

		 */

		while (next < max

		while (next <= max

			&& claim_block(sb_bgl_lock(sbi, group),

					next, bitmap_bh)) {

			next++;
@@ -2094,73 +2094,74 @@ static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb, 
 */

int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)

{

	ext3_grpblk_t last_block, first_block, free_blocks;

	unsigned long first_group, last_group;

	unsigned long group, ngroups;

	ext3_grpblk_t last_block, first_block;

	unsigned long group, first_group, last_group;

	struct ext3_group_desc *gdp;

	struct ext3_super_block *es = EXT3_SB(sb)->s_es;

	uint64_t start, len, minlen, trimmed;

	uint64_t start, minlen, end, trimmed = 0;

	ext3_fsblk_t first_data_blk =

			le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block);

	ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count);

	int ret = 0;



	start = (range->start >> sb->s_blocksize_bits) +

		le32_to_cpu(es->s_first_data_block);

	len = range->len >> sb->s_blocksize_bits;

	start = range->start >> sb->s_blocksize_bits;

	end = start + (range->len >> sb->s_blocksize_bits) - 1;

	minlen = range->minlen >> sb->s_blocksize_bits;

	trimmed = 0;



	if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb)))

	if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb)) ||

	    unlikely(start >= max_blks))

		return -EINVAL;

	if (start >= max_blks)

		return -EINVAL;

	if (start + len > max_blks)

		len = max_blks - start;

	if (end >= max_blks)

		end = max_blks - 1;

	if (end <= first_data_blk)

		goto out;

	if (start < first_data_blk)

		start = first_data_blk;



	ngroups = EXT3_SB(sb)->s_groups_count;

	smp_rmb();



	/* Determine first and last group to examine based on start and len */

	ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start,

				     &first_group, &first_block);

	ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) (start + len),

	ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) end,

				     &last_group, &last_block);

	last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group;

	last_block = EXT3_BLOCKS_PER_GROUP(sb);



	if (first_group > last_group)

		return -EINVAL;

	/* end now represents the last block to discard in this group */

	end = EXT3_BLOCKS_PER_GROUP(sb) - 1;



	for (group = first_group; group <= last_group; group++) {

		gdp = ext3_get_group_desc(sb, group, NULL);

		if (!gdp)

			break;



		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);

		if (free_blocks < minlen)

			continue;



		/*

		 * For all the groups except the last one, last block will

		 * always be EXT3_BLOCKS_PER_GROUP(sb), so we only need to

		 * change it for the last group in which case first_block +

		 * len < EXT3_BLOCKS_PER_GROUP(sb).

		 * always be EXT3_BLOCKS_PER_GROUP(sb)-1, so we only need to

		 * change it for the last group, note that last_block is

		 * already computed earlier by ext3_get_group_no_and_offset()

		 */

		if (first_block + len < EXT3_BLOCKS_PER_GROUP(sb))

			last_block = first_block + len;

		len -= last_block - first_block;

		if (group == last_group)

			end = last_block;



		if (le16_to_cpu(gdp->bg_free_blocks_count) >= minlen) {

			ret = ext3_trim_all_free(sb, group, first_block,

					last_block, minlen);

						 end, minlen);

			if (ret < 0)

				break;



			trimmed += ret;

		}



		/*

		 * For every group except the first one, we are sure

		 * that the first block to discard will be block #0.

		 */

		first_block = 0;

	}



	if (ret >= 0)

	if (ret > 0)

		ret = 0;

	range->len = trimmed * sb->s_blocksize;



out:

	range->len = trimmed * sb->s_blocksize;

	return ret;

}