From: Si-Wei Liu <si-wei.liu@xxxxxxxxxx> commit ed7f2afdd0e043a397677e597ced0830b83ba0b3 upstream. 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> Link: https://patch.msgid.link/20240724170452.16837-2-dongli.zhang@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/tap.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -1153,6 +1153,11 @@ static int tap_get_user_xdp(struct tap_q 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); Patches currently in stable-queue which might be from si-wei.liu@xxxxxxxxxx are queue-5.4/tap-add-missing-verification-for-short-frame.patch queue-5.4/tun-add-missing-verification-for-short-frame.patch
