netdev - [PATCH net] ipv6: fix crash on ICMPv6 redirects with prohibited/blackholed source

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Message-Id: <bf7886537e41d9e9ac1a0d901283daf22b0b5df1.1446419326.git.mschiffer@universe-factory.net>
Date:	Mon,  2 Nov 2015 00:10:35 +0100
From:	Matthias Schiffer <mschiffer@...verse-factory.net>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org
Subject: [PATCH net] ipv6: fix crash on ICMPv6 redirects with prohibited/blackholed source

There are other error values besides ip6_null_entry that can be returned by
ip6_route_redirect(): fib6_rule_action() can also result in
ip6_blk_hole_entry and ip6_prohibit_entry if such ip rules are installed.

Only checking for ip6_null_entry in rt6_do_redirect() causes ip6_ins_rt()
to be called with rt->rt6i_table == NULL in these cases, making the kernel
crash.

Signed-off-by: Matthias Schiffer <mschiffer@...verse-factory.net>
---

This bug exists pretty much forever, please queue up for all -stable
kernels.


 net/ipv6/route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 946880a..c196ed7 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2160,7 +2160,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 	}
 
 	rt = (struct rt6_info *) dst;
-	if (rt == net->ipv6.ip6_null_entry) {
+	if (rt->rt6i_flags & RTF_REJECT) {
 		net_dbg_ratelimited("rt6_redirect: source isn't a valid nexthop for redirect target\n");
 		return;
 	}
-- 
2.6.2

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