From: Dongli Zhang <dongli.zhang@xxxxxxxxxx> commit 049584807f1d797fc3078b68035450a9769eb5c3 upstream. The cited commit missed to check against the validity of the frame length in the tun_xdp_one() path, which could cause a corrupted skb to be sent downstack. Even before the skb is transmitted, the tun_xdp_one-->eth_type_trans() may access the Ethernet header although it can be less 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, tun_get_user() already prohibits short frame which has the length less than Ethernet header size from being transmitted for IFF_TAP. This is to drop any frame shorter than the Ethernet header size just like how tun_get_user() does. CVE: CVE-2024-41091 Inspired-by: https://lore.kernel.org/netdev/1717026141-25716-1-git-send-email-si-wei.liu@xxxxxxxxxx/ Fixes: 043d222f93ab ("tuntap: accept an array of XDP buffs through sendmsg()") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx> Reviewed-by: Si-Wei Liu <si-wei.liu@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/20240724170452.16837-3-dongli.zhang@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/tun.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2539,6 +2539,9 @@ static int tun_xdp_one(struct tun_struct bool skb_xdp = false; struct page *page; + if (unlikely(datasize < ETH_HLEN)) + return -EINVAL; + xdp_prog = rcu_dereference(tun->xdp_prog); if (xdp_prog) { if (gso->gso_type) { Patches currently in stable-queue which might be from dongli.zhang@xxxxxxxxxx are queue-5.4/tap-add-missing-verification-for-short-frame.patch queue-5.4/tun-add-missing-verification-for-short-frame.patch
