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ipv4: Fix peer validation on cached lookup. 

If ipv4_valdiate_peer() fails during a cached entry lookup,
we'll NULL derer since the loop iterator assumes rth is not
NULL.

Letting this be handled as a failure is just bogus, so just make it
not fail.  If we have trouble getting a non-NULL neighbour for the
redirected gateway, just restore the original gateway and continue.

The very next use of this cached route will try again.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2011-12-05 13:21:42 -05:00
parent f61759e6b8
commit de398fb8b9
1 changed files with 13 additions and 22 deletions
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35
net/ipv4/route.c
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@ -1310,7 +1310,7 @@ static void rt_del(unsigned hash, struct rtable *rt)
spin_unlock_bh(rt_hash_lock_addr(hash));
}
static int check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
static void check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
{
struct rtable *rt = (struct rtable *) dst;
__be32 orig_gw = rt->rt_gateway;
@ -1321,21 +1321,19 @@ static int check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
rt->rt_gateway = peer->redirect_learned.a4;
n = ipv4_neigh_lookup(&rt->dst, &rt->rt_gateway);
if (IS_ERR(n))
return PTR_ERR(n);
if (IS_ERR(n)) {
rt->rt_gateway = orig_gw;
return;
}
old_n = xchg(&rt->dst._neighbour, n);
if (old_n)
neigh_release(old_n);
if (!n || !(n->nud_state & NUD_VALID)) {
if (n)
neigh_event_send(n, NULL);
rt->rt_gateway = orig_gw;
return -EAGAIN;
if (!(n->nud_state & NUD_VALID)) {
neigh_event_send(n, NULL);
} else {
rt->rt_flags |= RTCF_REDIRECTED;
call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
}
return 0;
}
/* called in rcu_read_lock() section */
@ -1693,7 +1691,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
}
static struct rtable *ipv4_validate_peer(struct rtable *rt)
static void ipv4_validate_peer(struct rtable *rt)
{
if (rt->rt_peer_genid != rt_peer_genid()) {
struct inet_peer *peer;
@ -1708,15 +1706,12 @@ static struct rtable *ipv4_validate_peer(struct rtable *rt)
if (peer->redirect_genid != redirect_genid)
peer->redirect_learned.a4 = 0;
if (peer->redirect_learned.a4 &&
peer->redirect_learned.a4 != rt->rt_gateway) {
if (check_peer_redir(&rt->dst, peer))
return NULL;
}
peer->redirect_learned.a4 != rt->rt_gateway)
check_peer_redir(&rt->dst, peer);
}
rt->rt_peer_genid = rt_peer_genid();
}
return rt;
}
static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
@ -1725,7 +1720,7 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
if (rt_is_expired(rt))
return NULL;
dst = (struct dst_entry *) ipv4_validate_peer(rt);
ipv4_validate_peer(rt);
return dst;
}
@ -2380,9 +2375,7 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
rth->rt_mark == skb->mark &&
net_eq(dev_net(rth->dst.dev), net) &&
!rt_is_expired(rth)) {
rth = ipv4_validate_peer(rth);
if (!rth)
continue;
ipv4_validate_peer(rth);
if (noref) {
dst_use_noref(&rth->dst, jiffies);
skb_dst_set_noref(skb, &rth->dst);
@ -2758,9 +2751,7 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *flp4)
(IPTOS_RT_MASK | RTO_ONLINK)) &&
net_eq(dev_net(rth->dst.dev), net) &&
!rt_is_expired(rth)) {
rth = ipv4_validate_peer(rth);
if (!rth)
continue;
ipv4_validate_peer(rth);
dst_use(&rth->dst, jiffies);
RT_CACHE_STAT_INC(out_hit);
rcu_read_unlock_bh();