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virtio-net: fix possible unsigned integer overflow

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When the single-buffer xdp is loaded and after xdp_linearize_page()
is called, *num_buf becomes 0 and (*num_buf - 1) may overflow into
a large integer in virtnet_build_xdp_buff_mrg(), resulting in
unexpected packet dropping.

Fixes: ef75cb51f139 ("virtio-net: build xdp_buff with multi buffers")
Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20230131085004.98687-1-hengqi@linux.alibaba.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Heng Qi 2023-01-31 16:50:04 +08:00 committed by Jakub Kicinski
parent 028fb19c6b
commit 981f14d42a
1 changed files with 9 additions and 6 deletions
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15
drivers/net/virtio_net.c
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@ -723,7 +723,7 @@ static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
* have enough headroom.
*/
static struct page *xdp_linearize_page(struct receive_queue *rq,
u16 *num_buf,
int *num_buf,
struct page *p,
int offset,
int page_off,
@ -823,7 +823,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {
int offset = buf - page_address(page) + header_offset;
unsigned int tlen = len + vi->hdr_len;
u16 num_buf = 1;
int num_buf = 1;
xdp_headroom = virtnet_get_headroom(vi);
header_offset = VIRTNET_RX_PAD + xdp_headroom;
@ -996,7 +996,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
void *buf,
unsigned int len,
unsigned int frame_sz,
u16 *num_buf,
int *num_buf,
unsigned int *xdp_frags_truesize,
struct virtnet_rq_stats *stats)
{
@ -1014,6 +1014,9 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
xdp_prepare_buff(xdp, buf - VIRTIO_XDP_HEADROOM,
VIRTIO_XDP_HEADROOM + vi->hdr_len, len - vi->hdr_len, true);
if (!*num_buf)
return 0;
if (*num_buf > 1) {
/* If we want to build multi-buffer xdp, we need
* to specify that the flags of xdp_buff have the
@ -1027,10 +1030,10 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
shinfo->xdp_frags_size = 0;
}
if ((*num_buf - 1) > MAX_SKB_FRAGS)
if (*num_buf > MAX_SKB_FRAGS + 1)
return -EINVAL;
while ((--*num_buf) >= 1) {
while (--*num_buf > 0) {
buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
if (unlikely(!buf)) {
pr_debug("%s: rx error: %d buffers out of %d missing\n",
@ -1083,7 +1086,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
struct virtnet_rq_stats *stats)
{
struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
struct page *page = virt_to_head_page(buf);
int offset = buf - page_address(page);
struct sk_buff *head_skb, *curr_skb;