2021-12-24 10:10:39

by Jiasheng Jiang

Subject: [PATCH] virtio_ring: Check null pointer

As the alloc_indirect_packed() returns kmalloc_array() that could
allocation fail and return null pointer, it should be check in order to
prevent the dereference of null pointer.

Fixes: 1ce9e6055fa0 ("virtio_ring: introduce packed ring support")
Signed-off-by: Jiasheng Jiang <[email protected]>
---
drivers/virtio/virtio_ring.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 71e16b53e9c1..30fd925165ac 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -991,7 +991,12 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
dma_addr_t addr;

head = vq->packed.next_avail_idx;
+
desc = alloc_indirect_packed(total_sg, gfp);
+ if (!desc) {
+ END_USE(vq);
+ return -ENOMEM;
+ }

if (unlikely(vq->vq.num_free < 1)) {
pr_debug("Can't add buf len 1 - avail = 0\n");
--
2.25.1

2022-01-04 03:42:18

by Jason Wang

Subject: Re: [PATCH] virtio_ring: Check null pointer

On Fri, Dec 24, 2021 at 6:10 PM Jiasheng Jiang <[email protected]> wrote:
>
> As the alloc_indirect_packed() returns kmalloc_array() that could
> allocation fail and return null pointer, it should be check in order to
> prevent the dereference of null pointer.
>
> Fixes: 1ce9e6055fa0 ("virtio_ring: introduce packed ring support")
> Signed-off-by: Jiasheng Jiang <[email protected]>
> ---
> drivers/virtio/virtio_ring.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 71e16b53e9c1..30fd925165ac 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -991,7 +991,12 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
> dma_addr_t addr;
>
> head = vq->packed.next_avail_idx;
> +

Unnecessary changes.

Other than this:

Acked-by: Jason Wang <[email protected]>

> desc = alloc_indirect_packed(total_sg, gfp);
> + if (!desc) {
> + END_USE(vq);
> + return -ENOMEM;
> + }
>
> if (unlikely(vq->vq.num_free < 1)) {
> pr_debug("Can't add buf len 1 - avail = 0\n");
> --
> 2.25.1
>