ext4: fix possible overflow in ext4_trim_fs() (4f531501) · Commits · 戴 / test

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:

Lukas Czerner <lczerner@redhat.com>

fs/ext4/mballoc.c

+6 −0

Original line number	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)
		{
		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 group, ngroups = ext4_get_groups_count(sb);
		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;
		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)))
		return -EINVAL;

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