On Mon, Jul 14, 2025 at 04:20:56PM +0100, Will Deacon wrote:
When receiving a vsock packet in the guest, only the virtqueue buffer
size is validated prior to virtio_vsock_skb_rx_put(). Unfortunately,
virtio_vsock_skb_rx_put() uses the length from the packet header as the
length argument to skb_put(), potentially resulting in SKB overflow if
the host has gone wonky.
Validate the length as advertised by the packet header before calling
virtio_vsock_skb_rx_put().
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
net/vmw_vsock/virtio_transport.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index f0e48e6911fc..bd2c6aaa1a93 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -624,8 +624,9 @@ static void virtio_transport_rx_work(struct work_struct *work)
do {
virtqueue_disable_cb(vq);
for (;;) {
+ unsigned int len, payload_len;
+ struct virtio_vsock_hdr *hdr;
struct sk_buff *skb;
- unsigned int len;
if (!virtio_transport_more_replies(vsock)) {
/* Stop rx until the device processes already
@@ -642,12 +643,19 @@ static void virtio_transport_rx_work(struct work_struct *work)
vsock->rx_buf_nr--;
/* Drop short/long packets */
- if (unlikely(len < sizeof(struct virtio_vsock_hdr) ||
+ if (unlikely(len < sizeof(*hdr) ||
pre-existing: in some part we use sizeof(*hdr) in other
VIRTIO_VSOCK_SKB_HEADROOM, I think we should try to uniform that, but of
course not for this series!
len > virtio_vsock_skb_len(skb))) {
kfree_skb(skb);
continue;
}
+ hdr = virtio_vsock_hdr(skb);
+ payload_len = le32_to_cpu(hdr->len);
+ if (payload_len > len - sizeof(*hdr)) {
Since this is an hot path, should we use `unlikely`, like in the
previous check, to instruct the branch predictor?
The rest LGTM!
Thanks,
Stefano
+ kfree_skb(skb);
+ continue;
+ }
+
virtio_vsock_skb_rx_put(skb);
virtio_transport_deliver_tap_pkt(skb);
virtio_transport_recv_pkt(&virtio_transport, skb);
--
2.50.0.727.gbf7dc18ff4-goog
