linux-kernel - [PATCH 3.16 205/233] ipv6: Do not leak throw route references

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Date:   Sat, 09 Sep 2017 22:47:15 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Serhey Popovych" <serhe.popovych@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.16 205/233] ipv6: Do not leak throw route references

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Serhey Popovych <serhe.popovych@...il.com>

commit 07f615574f8ac499875b21c1142f26308234a92c upstream.

While commit 73ba57bfae4a ("ipv6: fix backtracking for throw routes")
does good job on error propagation to the fib_rules_lookup()
in fib rules core framework that also corrects throw routes
handling, it does not solve route reference leakage problem
happened when we return -EAGAIN to the fib_rules_lookup()
and leave routing table entry referenced in arg->result.

If rule with matched throw route isn't last matched in the
list we overwrite arg->result losing reference on throw
route stored previously forever.

We also partially revert commit ab997ad40839 ("ipv6: fix the
incorrect return value of throw route") since we never return
routing table entry with dst.error == -EAGAIN when
CONFIG_IPV6_MULTIPLE_TABLES is on. Also there is no point
to check for RTF_REJECT flag since it is always set throw
route.

Fixes: 73ba57bfae4a ("ipv6: fix backtracking for throw routes")
Signed-off-by: Serhey Popovych <serhe.popovych@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16: commit ab997ad40839 was never applied here and does
 not need to be reverted]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -105,7 +105,8 @@ static int fib6_rule_action(struct fib_r
 			flp6->saddr = saddr;
 		}
 		err = rt->dst.error;
-		goto out;
+		if (err != -EAGAIN)
+			goto out;
 	}
 again:
 	ip6_rt_put(rt);