From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Si-Wei Liu Date: Wed, 24 Jul 2024 10:04:51 -0700 Subject: [PATCH] tap: add missing verification for short frame 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@oracle.com/ Fixes: 0efac27791ee ("tap: accept an array of XDP buffs through sendmsg()") Cc: stable@vger.kernel.org Signed-off-by: Si-Wei Liu Signed-off-by: Dongli Zhang Reviewed-by: Willem de Bruijn Reviewed-by: Paolo Abeni Reviewed-by: Jason Wang Link: https://patch.msgid.link/20240724170452.16837-2-dongli.zhang@oracle.com Signed-off-by: Jakub Kicinski (cherry picked from commit ed7f2afdd0e043a397677e597ced0830b83ba0b3) Signed-off-by: Fiona Ebner --- drivers/net/tap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index 9f0495e8df4d..feeeac715c18 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);