Commit 8dd27fec authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
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ext4: check for out-of-order index extents in ext4_valid_extent_entries() 



After commit 5946d089 ("ext4: check for overlapping extents in
ext4_valid_extent_entries()"), we can check out the overlapping extent
entry in leaf extent blocks. But the out-of-order extent entry in index
extent blocks could also trigger bad things if the filesystem is
inconsistent. So this patch add a check to figure out the out-of-order
index extents and return error.

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarTheodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210908120850.4012324-2-yi.zhang@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 31d21d21

fs/ext4/extents.c

+12 −5
Original line number Diff line number Diff line
@@ -357,6 +357,9 @@ static int ext4_valid_extent_entries(struct inode *inode, 
				     ext4_fsblk_t *pblk, int depth)

{

	unsigned short entries;

	ext4_lblk_t lblock = 0;

	ext4_lblk_t prev = 0;



	if (eh->eh_entries == 0)

		return 1;
@@ -365,31 +368,35 @@ static int ext4_valid_extent_entries(struct inode *inode, 
	if (depth == 0) {

		/* leaf entries */

		struct ext4_extent *ext = EXT_FIRST_EXTENT(eh);

		ext4_lblk_t lblock = 0;

		ext4_lblk_t prev = 0;

		int len = 0;

		while (entries) {

			if (!ext4_valid_extent(inode, ext))

				return 0;



			/* Check for overlapping extents */

			lblock = le32_to_cpu(ext->ee_block);

			len = ext4_ext_get_actual_len(ext);

			if ((lblock <= prev) && prev) {

				*pblk = ext4_ext_pblock(ext);

				return 0;

			}

			prev = lblock + ext4_ext_get_actual_len(ext) - 1;

			ext++;

			entries--;

			prev = lblock + len - 1;

		}

	} else {

		struct ext4_extent_idx *ext_idx = EXT_FIRST_INDEX(eh);

		while (entries) {

			if (!ext4_valid_extent_idx(inode, ext_idx))

				return 0;



			/* Check for overlapping index extents */

			lblock = le32_to_cpu(ext_idx->ei_block);

			if ((lblock <= prev) && prev) {

				*pblk = ext4_idx_pblock(ext_idx);

				return 0;

			}

			ext_idx++;

			entries--;

			prev = lblock;

		}

	}

	return 1;