From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
[ Upstream commit af8c53c8bc087459b1aadd4c94805d8272358d79 ]
If userspace asked fsmap to try to count the number of entries, we cannot
return more than UINT_MAX entries because fmh_entries is u32.
Therefore, stop counting if we hit this limit or else we will waste time
to return truncated results.
Fixes: 0c9ec4beecac ("ext4: support GETFSMAP ioctls")
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20201001222148.GA49520@magnolia
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/ext4/fsmap.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/ext4/fsmap.c b/fs/ext4/fsmap.c
index dbccf46f17709..37347ba868b70 100644
--- a/fs/ext4/fsmap.c
+++ b/fs/ext4/fsmap.c
@@ -108,6 +108,9 @@ static int ext4_getfsmap_helper(struct super_block *sb,
/* Are we just counting mappings? */
if (info->gfi_head->fmh_count == 0) {
+ if (info->gfi_head->fmh_entries == UINT_MAX)
+ return EXT4_QUERY_RANGE_ABORT;
+
if (rec_fsblk > info->gfi_next_fsblk)
info->gfi_head->fmh_entries++;
--
2.25.1
