ip_tunnel: fix panic in ip_tunnel_xmit()
Setting rt variable to NULL at the beginning of ip_tunnel_xmit()
missed possible use of this variable as a scratch value.
Also fixes a possible dst leak in tunnel_dst_check() :
If we had to call tunnel_dst_reset(), we forgot to
release the reference on dst.
Merges tunnel_dst_get()/tunnel_dst_check() into
a single tunnel_rtable_get() function for clarity.
Many thanks to Tommi for his report and tests.
Fixes: 7d442fab0a
("ipv4: Cache dst in tunnels")
Reported-by: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Tommi Rantala <tt.rantala@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -101,28 +101,22 @@ static void tunnel_dst_reset_all(struct ip_tunnel *t)
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__tunnel_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);
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}
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static struct dst_entry *tunnel_dst_get(struct ip_tunnel *t)
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static struct rtable *tunnel_rtable_get(struct ip_tunnel *t, u32 cookie)
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{
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struct dst_entry *dst;
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rcu_read_lock();
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dst = rcu_dereference(this_cpu_ptr(t->dst_cache)->dst);
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if (dst)
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dst_hold(dst);
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if (dst) {
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if (dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
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rcu_read_unlock();
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return dst;
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}
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static struct dst_entry *tunnel_dst_check(struct ip_tunnel *t, u32 cookie)
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{
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struct dst_entry *dst = tunnel_dst_get(t);
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if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
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tunnel_dst_reset(t);
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return NULL;
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}
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return dst;
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dst_hold(dst);
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}
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rcu_read_unlock();
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return (struct rtable *)dst;
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}
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/* Often modified stats are per cpu, other are shared (netdev->stats) */
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@ -584,7 +578,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
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struct flowi4 fl4;
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u8 tos, ttl;
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__be16 df;
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struct rtable *rt = NULL; /* Route to the other host */
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struct rtable *rt; /* Route to the other host */
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unsigned int max_headroom; /* The extra header space needed */
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__be32 dst;
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int err;
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@ -657,8 +651,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
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init_tunnel_flow(&fl4, protocol, dst, tnl_params->saddr,
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tunnel->parms.o_key, RT_TOS(tos), tunnel->parms.link);
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if (connected)
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rt = (struct rtable *)tunnel_dst_check(tunnel, 0);
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rt = connected ? tunnel_rtable_get(tunnel, 0) : NULL;
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if (!rt) {
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rt = ip_route_output_key(tunnel->net, &fl4);
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