From 0a2c717b65b4c563b3439ec84bdafff15c61f6d4 Mon Sep 17 00:00:00 2001 From: Shreyansh Chouhan Date: Sat, 21 Aug 2021 12:44:24 +0530 Subject: [PATCH] ip_gre: add validation for csum_start [ Upstream commit 1d011c4803c72f3907eccfc1ec63caefb852fcbf ] 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. Mot-CRs-fixed: (CR) CVE-Fixed: CVE-2021-39633 Bug: 150694665 Change-Id: I6e4d15fe38087e578434938959ff19e3252c951d 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 Signed-off-by: Sasha Levin Signed-off-by: Gajjala Chakradhar Reviewed-on: https://gerrit.mot.com/2152182 SLTApproved: Slta Waiver SME-Granted: SME Approvals Granted Tested-by: Jira Key Reviewed-by: Xiangpo Zhao Submit-Approved: Jira Key --- net/ipv4/ip_gre.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index dd3bcf22fe8b..94941d9442cf 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -446,6 +446,8 @@ 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); } -- 2.20.1