[PATCH 011/104] ipv6: don't stop backtracking in fib6_lookup_1 if subtree does not match

[Kamal Mostafa]

3.8.13.11 -stable review patch.  If anyone has any objections, please let me know.

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

From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit 3e3be275851bc6fc90bfdcd732cd95563acd982b ]

In case a subtree did not match we currently stop backtracking and return
NULL (root table from fib_lookup). This could yield in invalid routing
table lookups when using subtrees.

Instead continue to backtrack until a valid subtree or node is found
and return this match.

Also remove unneeded NULL check.

Reported-by: Teco Boot <teco@xxxxxxxxxx>
Cc: YOSHIFUJI Hideaki <yoshfuji@xxxxxxxxxxxxxx>
Cc: David Lamparter <equinox@xxxxxxxxxx>
Cc: <boutier@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 net/ipv6/ip6_fib.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index e67039f..7c39aa6 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -995,14 +995,22 @@ static struct fib6_node * fib6_lookup_1(struct fib6_node *root,
 
 			if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
 #ifdef CONFIG_IPV6_SUBTREES
-				if (fn->subtree)
-					fn = fib6_lookup_1(fn->subtree, args + 1);
+				if (fn->subtree) {
+					struct fib6_node *sfn;
+					sfn = fib6_lookup_1(fn->subtree,
+							    args + 1);
+					if (!sfn)
+						goto backtrack;
+					fn = sfn;
+				}
 #endif
-				if (!fn || fn->fn_flags & RTN_RTINFO)
+				if (fn->fn_flags & RTN_RTINFO)
 					return fn;
 			}
 		}
-
+#ifdef CONFIG_IPV6_SUBTREES
+backtrack:
+#endif
 		if (fn->fn_flags & RTN_ROOT)
 			break;
 
-- 
1.8.1.2

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