netdev - [PATCH] ip: ip_options_compile() resilient to NULL skb route

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Date:	Thu, 14 Apr 2011 05:03:34 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	David Miller <davem@...emloft.net>, lkml@...tdoyle.com,
	shimoda.hiroaki@...il.com, netdev@...r.kernel.org
Subject: [PATCH] ip: ip_options_compile() resilient to NULL skb route

Le mercredi 13 avril 2011 à 19:54 -0700, Stephen Hemminger a écrit :

> I like this because it lets the bridge be transparent.
> The existing options code adds entry in record route, and which
> is not desirable.

OK then, I realize I should have submitted a full patch, here it is.

Thanks !

[PATCH] ip: ip_options_compile() resilient to NULL skb route

Scot Doyle demonstrated ip_options_compile() could be called with an skb
without an attached route, using a setup involving a bridge, netfilter,
and forged IP packets.

Let's make ip_options_compile() a bit more robust, instead of changing
bridge/netfilter code.

Reported-by: Scot Doyle <lkml@...tdoyle.com>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
Cc: Hiroaki SHIMODA <shimoda.hiroaki@...il.com>
---
 net/ipv4/ip_options.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index 28a736f..c10ad63 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -329,7 +329,7 @@ int ip_options_compile(struct net *net,
 					pp_ptr = optptr + 2;
 					goto error;
 				}
-				if (skb) {
+				if (rt) {
 					memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
 					opt->is_changed = 1;
 				}
@@ -371,7 +371,7 @@ int ip_options_compile(struct net *net,
 						goto error;
 					}
 					opt->ts = optptr - iph;
-					if (skb) {
+					if (rt)  {
 						memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
 						timeptr = (__be32*)&optptr[optptr[2]+3];
 					}


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