crypto: skcipher - avoid NULL dereference

Stanse found a potential NULL dereference in ablkcipher_next_slow.
Even though kmalloc fails, its retval is dereferenced later. Return
from that function properly earlier.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 98a6610..a854df2a 100644
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -165,7 +165,7 @@
 
 	p = kmalloc(n, GFP_ATOMIC);
 	if (!p)
-		ablkcipher_walk_done(req, walk, -ENOMEM);
+		return ablkcipher_walk_done(req, walk, -ENOMEM);
 
 	base = p + 1;