Patch "virtio_net: bugfix overflow inside xdp_linearize_page()" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    virtio_net: bugfix overflow inside xdp_linearize_page()

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     virtio_net-bugfix-overflow-inside-xdp_linearize_page.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 41fc19a19e3156a690da26112bc3934589c83771
Author: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Date:   Fri Apr 14 14:08:35 2023 +0800

    virtio_net: bugfix overflow inside xdp_linearize_page()
    
    [ Upstream commit 853618d5886bf94812f31228091cd37d308230f7 ]
    
    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: 72979a6c3590 ("virtio_net: xdp, add slowpath case for non contiguous buffers")
    Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
    Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
    Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 20b1b34a092ad..3f1883814ce21 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -724,8 +724,13 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
 				       int page_off,
 				       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)
 		return NULL;
 
@@ -733,7 +738,6 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
 	page_off += *len;
 
 	while (--*num_buf) {
-		int tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 		unsigned int buflen;
 		void *buf;
 		int off;