block: limit vec count in bio_kmalloc() and bio_alloc_map_data()

Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

fs/bio.c

diff --git a/fs/bio.c b/fs/bio.c
index 8abb2df..8317a2c 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -370,6 +370,9 @@
 {
 	struct bio *bio;
 
+	if (nr_iovecs > UIO_MAXIOV)
+		return NULL;
+
 	bio = kmalloc(sizeof(struct bio) + nr_iovecs * sizeof(struct bio_vec),
 		      gfp_mask);
 	if (unlikely(!bio))
@@ -697,8 +700,12 @@
 static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
 					       gfp_t gfp_mask)
 {
-	struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);
+	struct bio_map_data *bmd;
 
+	if (iov_count > UIO_MAXIOV)
+		return NULL;
+
+	bmd = kmalloc(sizeof(*bmd), gfp_mask);
 	if (!bmd)
 		return NULL;