1 files changed, 29 insertions, 14 deletions

diff --git a/drivers/md/dm-clone-target.c b/drivers/md/dm-clone-target.c
index d1e1b5b56b1b..022dddcad647 100644
--- a/drivers/md/dm-clone-target.c
+++ b/drivers/md/dm-clone-target.c
@@ -293,10 +293,17 @@ static inline unsigned long bio_to_region(struct clone *clone, struct bio *bio)
 
 /* Get the region range covered by the bio */
 static void bio_region_range(struct clone *clone, struct bio *bio,
-			     unsigned long *rs, unsigned long *re)
+			     unsigned long *rs, unsigned long *nr_regions)
 {
+	unsigned long end;
+
 	*rs = dm_sector_div_up(bio->bi_iter.bi_sector, clone->region_size);
-	*re = bio_end_sector(bio) >> clone->region_shift;
+	end = bio_end_sector(bio) >> clone->region_shift;
+
+	if (*rs >= end)
+		*nr_regions = 0;
+	else
+		*nr_regions = end - *rs;
 }
 
 /* Check whether a bio overwrites a region */
@@ -454,7 +461,7 @@ static void trim_bio(struct bio *bio, sector_t sector, unsigned int len)
 
 static void complete_discard_bio(struct clone *clone, struct bio *bio, bool success)
 {
-	unsigned long rs, re;
+	unsigned long rs, nr_regions;
 
 	/*
 	 * If the destination device supports discards, remap and trim the
@@ -463,9 +470,9 @@ static void complete_discard_bio(struct clone *clone, struct bio *bio, bool succ
 	 */
 	if (test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags) && success) {
 		remap_to_dest(clone, bio);
-		bio_region_range(clone, bio, &rs, &re);
+		bio_region_range(clone, bio, &rs, &nr_regions);
 		trim_bio(bio, rs << clone->region_shift,
-			 (re - rs) << clone->region_shift);
+			 nr_regions << clone->region_shift);
 		generic_make_request(bio);
 	} else
 		bio_endio(bio);
@@ -473,12 +480,21 @@ static void complete_discard_bio(struct clone *clone, struct bio *bio, bool succ
 
 static void process_discard_bio(struct clone *clone, struct bio *bio)
 {
-	unsigned long rs, re;
+	unsigned long rs, nr_regions;
 
-	bio_region_range(clone, bio, &rs, &re);
-	BUG_ON(re > clone->nr_regions);
+	bio_region_range(clone, bio, &rs, &nr_regions);
+	if (!nr_regions) {
+		bio_endio(bio);
+		return;
+	}
 
-	if (unlikely(rs == re)) {
+	if (WARN_ON(rs >= clone->nr_regions || (rs + nr_regions) < rs ||
+		    (rs + nr_regions) > clone->nr_regions)) {
+		DMERR("%s: Invalid range (%lu + %lu, total regions %lu) for discard (%llu + %u)",
+		      clone_device_name(clone), rs, nr_regions,
+		      clone->nr_regions,
+		      (unsigned long long)bio->bi_iter.bi_sector,
+		      bio_sectors(bio));
 		bio_endio(bio);
 		return;
 	}
@@ -487,7 +503,7 @@ static void process_discard_bio(struct clone *clone, struct bio *bio)
 	 * The covered regions are already hydrated so we just need to pass
 	 * down the discard.
 	 */
-	if (dm_clone_is_range_hydrated(clone->cmd, rs, re - rs)) {
+	if (dm_clone_is_range_hydrated(clone->cmd, rs, nr_regions)) {
 		complete_discard_bio(clone, bio, true);
 		return;
 	}
@@ -1169,7 +1185,7 @@ static void process_deferred_discards(struct clone *clone)
 	int r = -EPERM;
 	struct bio *bio;
 	struct blk_plug plug;
-	unsigned long rs, re;
+	unsigned long rs, nr_regions;
 	struct bio_list discards = BIO_EMPTY_LIST;
 
 	spin_lock_irq(&clone->lock);
@@ -1185,14 +1201,13 @@ static void process_deferred_discards(struct clone *clone)
 
 	/* Update the metadata */
 	bio_list_for_each(bio, &discards) {
-		bio_region_range(clone, bio, &rs, &re);
+		bio_region_range(clone, bio, &rs, &nr_regions);
 		/*
 		 * A discard request might cover regions that have been already
 		 * hydrated. There is no need to update the metadata for these
 		 * regions.
 		 */
-		r = dm_clone_cond_set_range(clone->cmd, rs, re - rs);
-
+		r = dm_clone_cond_set_range(clone->cmd, rs, nr_regions);
 		if (unlikely(r))
 			break;
 	}