5.4-stable review patch. If anyone has any objections, please let me know.
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From: Bui Quang Minh minhquangbui99@gmail.com
commit 315dbdd7cdf6aa533829774caaf4d25f1fd20e73 upstream.
In xdp_linearize_page, when reading the following buffers from the ring, we forget to check the received length with the true allocate size. This can lead to an out-of-bound read. This commit adds that missing check.
Cc: stable@vger.kernel.org Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set") Signed-off-by: Bui Quang Minh minhquangbui99@gmail.com Acked-by: Jason Wang jasowang@redhat.com Link: https://patch.msgid.link/20250630144212.48471-2-minhquangbui99@gmail.com Signed-off-by: Paolo Abeni pabeni@redhat.com [ adapted virtqueue_get_buf() to virtqueue_get_buf_ctx() ] Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-)
--- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -394,6 +394,26 @@ static unsigned int mergeable_ctx_to_tru return (unsigned long)mrg_ctx & ((1 << MRG_CTX_HEADER_SHIFT) - 1); }
+static int check_mergeable_len(struct net_device *dev, void *mrg_ctx, + unsigned int len) +{ + unsigned int headroom, tailroom, room, truesize; + + truesize = mergeable_ctx_to_truesize(mrg_ctx); + headroom = mergeable_ctx_to_headroom(mrg_ctx); + tailroom = headroom ? sizeof(struct skb_shared_info) : 0; + room = SKB_DATA_ALIGN(headroom + tailroom); + + if (len > truesize - room) { + pr_debug("%s: rx error: len %u exceeds truesize %lu\n", + dev->name, len, (unsigned long)(truesize - room)); + dev->stats.rx_length_errors++; + return -1; + } + + return 0; +} + /* Called from bottom half context */ static struct sk_buff *page_to_skb(struct virtnet_info *vi, struct receive_queue *rq, @@ -639,7 +659,8 @@ static unsigned int virtnet_get_headroom * across multiple buffers (num_buf > 1), and we make sure buffers * have enough headroom. */ -static struct page *xdp_linearize_page(struct receive_queue *rq, +static struct page *xdp_linearize_page(struct net_device *dev, + struct receive_queue *rq, u16 *num_buf, struct page *p, int offset, @@ -659,18 +680,27 @@ static struct page *xdp_linearize_page(s memcpy(page_address(page) + page_off, page_address(p) + offset, *len); page_off += *len;
+ /* Only mergeable mode can go inside this while loop. In small mode, + * *num_buf == 1, so it cannot go inside. + */ while (--*num_buf) { unsigned int buflen; void *buf; + void *ctx; int off;
- buf = virtqueue_get_buf(rq->vq, &buflen); + buf = virtqueue_get_buf_ctx(rq->vq, &buflen, &ctx); if (unlikely(!buf)) goto err_buf;
p = virt_to_head_page(buf); off = buf - page_address(p);
+ if (check_mergeable_len(dev, ctx, buflen)) { + put_page(p); + goto err_buf; + } + /* guard against a misconfigured or uncooperative backend that * is sending packet larger than the MTU. */ @@ -745,7 +775,7 @@ static struct sk_buff *receive_small(str headroom = vi->hdr_len + header_offset; buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); - xdp_page = xdp_linearize_page(rq, &num_buf, page, + xdp_page = xdp_linearize_page(dev, rq, &num_buf, page, offset, header_offset, &tlen); if (!xdp_page) @@ -910,7 +940,7 @@ static struct sk_buff *receive_mergeable if (unlikely(num_buf > 1 || headroom < virtnet_get_headroom(vi))) { /* linearize data for XDP */ - xdp_page = xdp_linearize_page(rq, &num_buf, + xdp_page = xdp_linearize_page(dev, rq, &num_buf, page, offset, VIRTIO_XDP_HEADROOM, &len);