[PATCH net] ipvs: use skb_to_full_sk() helper

[Eric Dumazet <eric.dumazet@xxxxxxxxx>]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

SYNACK packets might be attached to request sockets.

Use skb_to_full_sk() helper to avoid illegal accesses to
inet_sk(skb->sk)

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of 
listener")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
---
 net/netfilter/ipvs/ip_vs_core.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 1e24fff53e4b..f57b4dcdb233 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1176,6 +1176,7 @@ ip_vs_out(struct netns_ipvs *ipvs, unsigned int hooknum, 
struct sk_buff *skb, in
        struct ip_vs_protocol *pp;
        struct ip_vs_proto_data *pd;
        struct ip_vs_conn *cp;
+       struct sock *sk;
 
        EnterFunction(11);
 
@@ -1183,13 +1184,12 @@ ip_vs_out(struct netns_ipvs *ipvs, unsigned int 
hooknum, struct sk_buff *skb, in
        if (skb->ipvs_property)
                return NF_ACCEPT;
 
+       sk = skb_to_full_sk(skb);
        /* Bad... Do not break raw sockets */
-       if (unlikely(skb->sk != NULL && hooknum == NF_INET_LOCAL_OUT &&
+       if (unlikely(sk && hooknum == NF_INET_LOCAL_OUT &&
                     af == AF_INET)) {
-               struct sock *sk = skb->sk;
-               struct inet_sock *inet = inet_sk(skb->sk);
 
-               if (inet && sk->sk_family == PF_INET && inet->nodefrag)
+               if (sk->sk_family == PF_INET && inet_sk(sk)->nodefrag)
                        return NF_ACCEPT;
        }
 
@@ -1681,6 +1681,7 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, 
struct sk_buff *skb, int
        struct ip_vs_conn *cp;
        int ret, pkts;
        int conn_reuse_mode;
+       struct sock *sk;
 
        /* Already marked as IPVS request or reply? */
        if (skb->ipvs_property)
@@ -1708,12 +1709,11 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, 
struct sk_buff *skb, int
        ip_vs_fill_iph_skb(af, skb, false, &iph);
 
        /* Bad... Do not break raw sockets */
-       if (unlikely(skb->sk != NULL && hooknum == NF_INET_LOCAL_OUT &&
+       sk = skb_to_full_sk(skb);
+       if (unlikely(sk && hooknum == NF_INET_LOCAL_OUT &&
                     af == AF_INET)) {
-               struct sock *sk = skb->sk;
-               struct inet_sock *inet = inet_sk(skb->sk);
 
-               if (inet && sk->sk_family == PF_INET && inet->nodefrag)
+               if (sk->sk_family == PF_INET && inet_sk(sk)->nodefrag)
                        return NF_ACCEPT;
        }
 


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