5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
[ Upstream commit 6018a266279b1a75143c7c0804dd08a5fc4c3e0b ]
When ip_vti device is set to the qdisc of the sfb type, the cb field
of the sent skb may be modified during enqueuing. Then,
slab-use-after-free may occur when ip_vti device sends IPv6 packets.
As commit f855691975bb ("xfrm6: Fix the nexthdr offset in
_decode_session6.") showed, xfrm_decode_session was originally intended
only for the receive path. IP6CB(skb)->nhoff is not set during
transmission. Therefore, set the cb field in the skb to 0 before
sending packets.
Fixes: f855691975bb ("xfrm6: Fix the nexthdr offset in _decode_session6.")
Signed-off-by: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv4/ip_vti.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index bd41354ed8c11..275f2ecf0ba60 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -314,12 +314,12 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
switch (skb->protocol) {
case htons(ETH_P_IP):
- xfrm_decode_session(skb, &fl, AF_INET);
memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
+ xfrm_decode_session(skb, &fl, AF_INET);
break;
case htons(ETH_P_IPV6):
- xfrm_decode_session(skb, &fl, AF_INET6);
memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+ xfrm_decode_session(skb, &fl, AF_INET6);
break;
default:
goto tx_err;
--
2.40.1
