linux-kernel - Re: [PATCH] virtio_ring: Check null pointer

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Message-ID: <CACGkMEuTn4uaS5dfudF-X-Y0Rw0wH9VXcTkVsZJ_TUtxXGMBVw@mail.gmail.com>
Date:   Tue, 4 Jan 2022 11:42:01 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     mst <mst@...hat.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] virtio_ring: Check null pointer

On Fri, Dec 24, 2021 at 6:10 PM Jiasheng Jiang <jiasheng@...as.ac.cn> 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 <jiasheng@...as.ac.cn>
> ---
>  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 <jasowang@...hat.com>

>         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
>