Commit 853618d5 authored by Xuan Zhuo's avatar Xuan Zhuo Committed by David S. Miller

virtio_net: bugfix overflow inside xdp_linearize_page()

Here we copy the data from the original buf to the new page. But we
not check that it may be overflow.

As long as the size received(including vnethdr) is greater than 3840
(PAGE_SIZE -VIRTIO_XDP_HEADROOM). Then the memcpy will overflow.

And this is completely possible, as long as the MTU is large, such
as 4096. In our test environment, this will cause crash. Since crash is
caused by the written memory, it is meaningless, so I do not include it.

Fixes: 72979a6c ("virtio_net: xdp, add slowpath case for non contiguous buffers")
Signed-off-by: default avatarXuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 30379334
...@@ -814,8 +814,13 @@ static struct page *xdp_linearize_page(struct receive_queue *rq, ...@@ -814,8 +814,13 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
int page_off, int page_off,
unsigned int *len) unsigned int *len)
{ {
struct page *page = alloc_page(GFP_ATOMIC); int tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
struct page *page;
if (page_off + *len + tailroom > PAGE_SIZE)
return NULL;
page = alloc_page(GFP_ATOMIC);
if (!page) if (!page)
return NULL; return NULL;
...@@ -823,7 +828,6 @@ static struct page *xdp_linearize_page(struct receive_queue *rq, ...@@ -823,7 +828,6 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
page_off += *len; page_off += *len;
while (--*num_buf) { while (--*num_buf) {
int tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
unsigned int buflen; unsigned int buflen;
void *buf; void *buf;
int off; int off;
......
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