This is a note to let you know that I've just added the patch titled
ext4: limit entries returned when counting fsmap records
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-limit-entries-returned-when-counting-fsmap-reco.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2ec2a6729fac8645a72060613f9826baa803f194
Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Date: Thu Oct 1 15:21:48 2020 -0700
ext4: limit entries returned when counting fsmap records
[ 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>
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++;
