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    Subject[PATCH v2 2/2] virtio-net: Prevent NULL dereference
    Date
    This patch prevents a NULL dereference when the user has passed a length
    longer than an actual buffer to virtio-net.

    Cc: Rusty Russell <rusty@rustcorp.com.au>
    Cc: "Michael S. Tsirkin" <mst@redhat.com>
    Cc: virtualization@lists.linux-foundation.org
    Cc: netdev@vger.kernel.org
    Cc: kvm@vger.kernel.org
    Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
    ---
    drivers/net/virtio_net.c | 12 +++++++++++-
    1 files changed, 11 insertions(+), 1 deletions(-)

    diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
    index bde0dec..4a53d2a 100644
    --- a/drivers/net/virtio_net.c
    +++ b/drivers/net/virtio_net.c
    @@ -208,12 +208,22 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
    return NULL;
    }

    - while (len) {
    + while (len && page) {
    set_skb_frag(skb, page, offset, &len);
    page = (struct page *)page->private;
    offset = 0;
    }

    + /*
    + * This is the case where we ran out of pages in our linked list, but
    + * supposedly have more data to read.
    + */
    + if (len > 0) {
    + pr_debug("%s: missing data to assemble skb\n", skb->dev->name);
    + dev_kfree_skb(skb);
    + return NULL;
    + }
    +
    if (page)
    give_pages(vi, page);

    --
    1.7.6.1


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