ipv4/fib_hash.c: fix NULL dereference

Unless I miss a guaranteed relation between between "f" and
"new_fa->fa_info" this patch is required for fixing a NULL dereference
introduced by commit a6501e080c318f8d4467679d17807f42b3a33cd5 ("[IPV4]
FIB_HASH: Reduce memory needs and speedup lookups") and spotted by the
Coverity checker.

Eric Dumazet says:

	Hum, you are right, kmem_cache_free() doesnt allow a NULL
	object, like kfree() does.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_hash.c b/net/ipv4/fib_hash.c
index 76b9c684cccd2ac6d159ea597c0e734ed26f4b05..8d58d85dfac678f4485078efe4f28c6a143f03d3 100644 (file)
--- a/net/ipv4/fib_hash.c
+++ b/net/ipv4/fib_hash.c
@@ -372,7 +372,8 @@ static struct fib_node *fib_find_node(struct fn_zone *fz, __be32 key)
 static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
 {
        struct fn_hash *table = (struct fn_hash *) tb->tb_data;
-       struct fib_node *new_f, *f;
+       struct fib_node *new_f = NULL;
+       struct fib_node *f;
        struct fib_alias *fa, *new_fa;
        struct fn_zone *fz;
        struct fib_info *fi;
@@ -496,7 +497,6 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
 
        err = -ENOBUFS;
 
-       new_f = NULL;
        if (!f) {
                new_f = kmem_cache_zalloc(fn_hash_kmem, GFP_KERNEL);
                if (new_f == NULL)
@@ -512,7 +512,7 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
        if (new_fa->fa_info != NULL) {
                new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
                if (new_fa == NULL)
-                       goto out_free_new_f;
+                       goto out;
        }
        new_fa->fa_info = fi;
        new_fa->fa_tos = tos;
@@ -540,9 +540,9 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
                  &cfg->fc_nlinfo, 0);
        return 0;
 
-out_free_new_f:
-       kmem_cache_free(fn_hash_kmem, new_f);
 out:
+       if (new_f)
+               kmem_cache_free(fn_hash_kmem, new_f);
        fib_release_info(fi);
        return err;
 }