Re: Connect hangs for a while before returns -1 with ECONNREFUSED on 3.2 for loopback

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 03 février 2012 à 16:15 +0100, Eric Dumazet a écrit :

> We omit to send RST packet in tcp_v4_send_reset()
> 
> because of this test :
> 
> if (skb_rtable(skb)->rt_type != RTN_LOCAL)
> 	return
> 
> At this point rt_type is RTN_UNICAST
> 
> 

Here is the fix, thanks again !

[PATCH] ipv4: fix a route regression

commit 813b3b5db83 (ipv4: Use caller's on-stack flowi as-is in output
route lookups.) added a regression.

Some callers of ip_route_output_slow() assumed their flow argument was
constant.

ip_route_output_slow() must leave with original content of various
fields.

Thanks to Yurij M. Plotnikov for providing a bug report including a
program to reproduce the problem.

Reported-by: Yurij M. Plotnikov <Yurij.Plotnikov@oktetlabs.ru>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
 net/ipv4/route.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index bcacf54..0f63240 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2633,19 +2633,15 @@ static struct rtable *ip_route_output_slow(struct net *net, struct flowi4 *fl4)
 	unsigned int flags = 0;
 	struct fib_result res;
 	struct rtable *rth;
-	__be32 orig_daddr;
-	__be32 orig_saddr;
-	int orig_oif;
+	__be32 orig_daddr = fl4->daddr;
+	__be32 orig_saddr = fl4->saddr;
+	int orig_oif = fl4->flowi4_oif;
 
 	res.fi		= NULL;
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	res.r		= NULL;
 #endif
 
-	orig_daddr = fl4->daddr;
-	orig_saddr = fl4->saddr;
-	orig_oif = fl4->flowi4_oif;
-
 	fl4->flowi4_iif = net->loopback_dev->ifindex;
 	fl4->flowi4_tos = tos & IPTOS_RT_MASK;
 	fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
@@ -2816,6 +2812,9 @@ make_route:
 
 out:
 	rcu_read_unlock();
+	fl4->flowi4_oif = orig_oif;
+	fl4->daddr = orig_daddr;
+	fl4->saddr = orig_saddr;
 	return rth;
 }