From: Si-Wei Liu <si-wei.liu@xxxxxxxxxx> The cited commit missed to check against the validity of the frame length in the tap_get_user_xdp() path, which could cause a corrupted skb to be sent downstack. Even before the skb is transmitted, the tap_get_user_xdp()-->skb_set_network_header() may assume the size is more than ETH_HLEN. Once transmitted, this could either cause out-of-bound access beyond the actual length, or confuse the underlayer with incorrect or inconsistent header length in the skb metadata. In the alternative path, tap_get_user() already prohibits short frame which has the length less than Ethernet header size from being transmitted. This is to drop any frame shorter than the Ethernet header size just like how tap_get_user() does. CVE: CVE-2024-41090 Link: https://lore.kernel.org/netdev/1717026141-25716-1-git-send-email-si-wei.liu@xxxxxxxxxx/ Fixes: 0efac27791ee ("tap: accept an array of XDP buffs through sendmsg()") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx> Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx> Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx> Reviewed-by: Paolo Abeni <pabeni@xxxxxxxxxx> Reviewed-by: Jason Wang <jasowang@xxxxxxxxxx> --- drivers/net/tap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index bfdd3875fe86..77574f7a3bd4 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -1177,6 +1177,11 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) struct sk_buff *skb; int err, depth; + if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) { + err = -EINVAL; + goto err; + } + if (q->flags & IFF_VNET_HDR) vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); -- 2.34.1
