[PATCH 5.14 660/849] virtio_ring: check desc == NULL when using indirect with packed

Greg Kroah-Hartman
2021-11-15T23:15:03Z

From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>

[ 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@linux.alibaba.com>
Link: https://lore.kernel.org/r/20211020112323.67466-3-xuanzhuo@linux.alibaba.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 3035bb6f54585..d1f47327f6cfe 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1065,6 +1065,8 @@ 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");
@@ -1176,6 +1178,7 @@ 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);

@@ -1191,9 +1194,14 @@ 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