From fda0916c0367952060de8ba0d03c71842bac2433 Mon Sep 17 00:00:00 2001 From: Jeremy Allison Date: Mon, 27 Jan 2025 16:13:09 -0800 Subject: [PATCH] tap: add missing verification for short frame jira VULN-8269 cve CVE-2024-41090 commit-author Si-Wei Liu commit ed7f2afdd0e043a397677e597ced0830b83ba0b3 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: Jeremy Allison --- drivers/net/tap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index b55f6806cba31..f5b923216ed02 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -1145,6 +1145,11 @@ 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);