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Commit 4f531501 authored by Lukas Czerner's avatar Lukas Czerner Committed by Theodore Ts'o
Browse files

ext4: fix possible overflow in ext4_trim_fs() 



When determining last group through ext4_get_group_no_and_offset() the
result may be wrong in cases when range->start and range-len are too
big, because it may overflow when summing up those two numbers.

Fix that by checking range->len and limit its value to
ext4_blocks_count(). This commit was tested by myself with expected
result.

Signed-off-by: default avatarLukas Czerner <lczerner@redhat.com>
parent b72143ab

fs/ext4/mballoc.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -4819,6 +4819,7 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b, 
int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)

int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)

{

{

	struct ext4_buddy e4b;

	struct ext4_buddy e4b;

	ext4_fsblk_t blocks_count = ext4_blocks_count(EXT4_SB(sb)->s_es);

	ext4_group_t first_group, last_group;

	ext4_group_t first_group, last_group;

	ext4_group_t group, ngroups = ext4_get_groups_count(sb);

	ext4_group_t group, ngroups = ext4_get_groups_count(sb);

	ext4_grpblk_t cnt = 0, first_block, last_block;

	ext4_grpblk_t cnt = 0, first_block, last_block;
@@ -4830,6 +4831,11 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range) 
	minlen = range->minlen >> sb->s_blocksize_bits;

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

	trimmed = 0;

	trimmed = 0;





	if (start >= blocks_count)

		return -EINVAL;

	if (start + len > blocks_count)

		len = blocks_count - start;



	if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb)))

	if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb)))

		return -EINVAL;

		return -EINVAL;