Commit 439c5af4 authored by Shreyansh Chouhan's avatar Shreyansh Chouhan Committed by Yang Yingliang
Browse files

ip_gre: add validation for csum_start 



stable inclusion
from linux-4.19.206
commit c33471daf2763c5aee2b7926202c74b75c365119

--------------------------------

[ Upstream commit 1d011c48 ]

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: c5441932 ("GRE: Refactor GRE tunneling code.")
Reported-by: default avatar <syzbot+ff8e1b9f2f36481e2efc@syzkaller.appspotmail.com>
Signed-off-by: default avatarShreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
parent c68e152b

net/ipv4/ip_gre.c

+2 −0
Original line number Diff line number Diff line
@@ -449,6 +449,8 @@ 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);

}