Subject: [PATCH] fib_trie: Fix potential null pointer dereference

From: Firo Yang <[email-masked]>
Date: Sat, 6 Jun 2015 19:35:53 +0800

A smatch warning.
When kmem_cache_alloc() failed to alloc memory, a null pointer
will be returned. Redeference null pointer will generate
an unnecessary oops. So, use it after check.

Signed-off-by: Firo Yang <[email-masked]>
---
 net/ipv4/fib_trie.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 01bce15..34094c7 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -326,12 +326,13 @@ static inline void empty_child_dec(struct key_vector *n)
 static struct key_vector *leaf_new(t_key key, struct fib_alias *fa)
 {
 	struct tnode *kv = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
-	struct key_vector *l = kv->kv;
+	struct key_vector *l;
 
 	if (!kv)
 		return NULL;
 
 	/* initialize key vector */
+	l = kv->kv;
 	l->key = key;
 	l->pos = 0;
 	l->bits = 0;
-- 
2.4.2