[PATCH 1/2] block: prevent an integer overflow in bvec_try_merge_hw_page

[Christoph Hellwig <hch@lst.de>]

Reordered a check to avoid a possible overflow when adding len to bv_len.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index 816d412c06e9b4..cef830adbc06e0 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -944,7 +944,7 @@ bool bvec_try_merge_hw_page(struct request_queue *q, struct bio_vec *bv,
 
 	if ((addr1 | mask) != (addr2 | mask))
 		return false;
-	if (bv->bv_len + len > queue_max_segment_size(q))
+	if (len > queue_max_segment_size(q) - bv->bv_len)
 		return false;
 	return bvec_try_merge_page(bv, page, len, offset, same_page);
 }
-- 
2.39.2