9p/virtio: fix off-by-one error in sg list bounds check

Because the value of limit is VIRTQUEUE_NUM, if index is equal to limit, it will cause sg array out of bounds, so correct the judgement of BUG_ON. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Yiwen Jiang <[email protected]> Reported-By: Dan Carpenter <[email protected]> Acked-by: Jun Piao <[email protected]> Cc: [email protected] Signed-off-by: Dominique Martinet <[email protected]>
ambv · Aug 13, 2018 · 23cba9c · 23cba9c
1 parent c69f297
commit 23cba9c
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
@@ -191,7 +191,7 @@ static int pack_sg_list(struct scatterlist *sg, int start,
 		s = rest_of_page(data);
 		if (s > count)
 			s = count;
-		BUG_ON(index > limit);
+		BUG_ON(index >= limit);
 		/* Make sure we don't terminate early. */
 		sg_unmark_end(&sg[index]);
 		sg_set_buf(&sg[index++], data, s);
@@ -236,6 +236,7 @@ pack_sg_list_p(struct scatterlist *sg, int start, int limit,
 		s = PAGE_SIZE - data_off;
 		if (s > count)
 			s = count;
+		BUG_ON(index >= limit);
 		/* Make sure we don't terminate early. */
 		sg_unmark_end(&sg[index]);
 		sg_set_page(&sg[index++], pdata[i++], s, data_off);