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zhengchaoshaoklassert
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ip_vti: fix potential slab-use-after-free in decode_session6
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 f855691 ("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: f855691 ("xfrm6: Fix the nexthdr offset in _decode_session6.") Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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net/ipv4/ip_vti.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -287,12 +287,12 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
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288288
switch (skb->protocol) {
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case htons(ETH_P_IP):
290-
xfrm_decode_session(skb, &fl, AF_INET);
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memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
291+
xfrm_decode_session(skb, &fl, AF_INET);
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break;
293293
case htons(ETH_P_IPV6):
294-
xfrm_decode_session(skb, &fl, AF_INET6);
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memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
295+
xfrm_decode_session(skb, &fl, AF_INET6);
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break;
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default:
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goto tx_err;

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