[PATCH] btrfs: trim: Check the range passed into to prevent overflow

[Qu Wenruo <wqu@suse.com>]

Normally the range->len is set to default value (U64_MAX), but when it's
not default value, we should check if the range overflows.

And if overflows, return -EINVAL before doing anything.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/extent-tree.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f79e477a378e..62bfba6d3c07 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11245,6 +11245,7 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	struct btrfs_device *device;
 	struct list_head *devices;
 	u64 group_trimmed;
+	u64 range_end = U64_MAX;
 	u64 start;
 	u64 end;
 	u64 trimmed = 0;
@@ -11254,16 +11255,23 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	int dev_ret = 0;
 	int ret = 0;
 
+	/*
+	 * Check range overflow if range->len is set.
+	 * The default range->len is U64_MAX.
+	 */
+	if (range->len != U64_MAX && check_add_overflow(range->start,
+				range->len, &range_end))
+		return -EINVAL;
+
 	cache = btrfs_lookup_first_block_group(fs_info, range->start);
 	for (; cache; cache = next_block_group(cache)) {
-		if (cache->key.objectid >= (range->start + range->len)) {
+		if (cache->key.objectid >= range_end) {
 			btrfs_put_block_group(cache);
 			break;
 		}
 
 		start = max(range->start, cache->key.objectid);
-		end = min(range->start + range->len,
-				cache->key.objectid + cache->key.offset);
+		end = min(range_end, cache->key.objectid + cache->key.offset);
 
 		if (end - start >= range->minlen) {
 			if (!block_group_cache_done(cache)) {
-- 
2.21.0