From: Shreyansh Chouhan <chouhan.shreyansh630@xxxxxxxxx>
[ 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.
Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
Reported-by: syzbot+ff8e1b9f2f36481e2efc@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@xxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 9609ad71dd26..fe1801d9f059 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -353,6 +353,8 @@ 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);
}
--
2.30.2
