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: Lukas Czerner <lczerner@redhat.com>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 46d5414..7c603a0 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4819,6 +4819,7 @@
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 @@
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;