[PATCH 5.10 464/575] virtio_ring: check desc == NULL when using indirect with packed

[Greg Kroah-Hartman]

From: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>

[ Upstream commit fc6d70f40b3d0b3219e2026d05be0409695f620d ]

When using indirect with packed, we don't check for allocation failures.
This patch checks that and fall back on direct.

Fixes: 1ce9e6055fa0 ("virtio_ring: introduce packed ring support")
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211020112323.67466-3-xuanzhuo@xxxxxxxxxxxxxxxxx
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 6c730d6d50f71..e9432dbbec0a7 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -992,6 +992,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 
 	head = vq->packed.next_avail_idx;
 	desc = alloc_indirect_packed(total_sg, gfp);
+	if (!desc)
+		return -ENOMEM;
 
 	if (unlikely(vq->vq.num_free < 1)) {
 		pr_debug("Can't add buf len 1 - avail = 0\n");
@@ -1103,6 +1105,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 	unsigned int i, n, c, descs_used, err_idx;
 	__le16 head_flags, flags;
 	u16 head, id, prev, curr, avail_used_flags;
+	int err;
 
 	START_USE(vq);
 
@@ -1118,9 +1121,14 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 
 	BUG_ON(total_sg == 0);
 
-	if (virtqueue_use_indirect(_vq, total_sg))
-		return virtqueue_add_indirect_packed(vq, sgs, total_sg,
-				out_sgs, in_sgs, data, gfp);
+	if (virtqueue_use_indirect(_vq, total_sg)) {
+		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
+						    in_sgs, data, gfp);
+		if (err != -ENOMEM)
+			return err;
+
+		/* fall back on direct */
+	}
 
 	head = vq->packed.next_avail_idx;
 	avail_used_flags = vq->packed.avail_used_flags;
-- 
2.33.0