From de398fb8b92eba3447298053a483727bdd5fe37e Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 5 Dec 2011 13:21:42 -0500 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/ipv4/route.c | 35 +++++++++++++---------------------- 1 file changed, 13 insertions(+), 22 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 588d971a3ba1..46af62363b8c 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -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(); -- 2.39.2