From: Shreyansh Chouhan Date: Sat, 21 Aug 2021 07:14:24 +0000 (+0530) Subject: ip_gre: add validation for csum_start X-Git-Tag: v5.14~20^2~26 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=1d011c4803c72f3907eccfc1ec63caefb852fcbf;p=linux-2.6-block.git ip_gre: add validation for csum_start Validate csum_start in gre_handle_offloads before we call _gre_xmit so that we do not crash later when the csum_start value is used in the lco_csum function call. This patch deals with ipv4 code. Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.") Reported-by: syzbot+ff8e1b9f2f36481e2efc@syzkaller.appspotmail.com Signed-off-by: Shreyansh Chouhan Reviewed-by: Willem de Bruijn Signed-off-by: David S. Miller --- diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 12dca0c85f3c..95419b7adf5c 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -473,6 +473,8 @@ static void __gre_xmit(struct sk_buff *skb, struct net_device *dev, static int gre_handle_offloads(struct sk_buff *skb, bool csum) { + if (csum && skb_checksum_start(skb) < skb->data) + return -EINVAL; return iptunnel_handle_offloads(skb, csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE); }