crypto: algif_skcipher - set error code when kcalloc fails

Fix bug https://bugzilla.kernel.org/show_bug.cgi?id=188521. In function
skcipher_recvmsg_async(), variable err takes the return value, and its
value should be negative on failures. Because variable err may be
reassigned and checked before calling kcalloc(), its value may be 0
(indicates no error) even if kcalloc() fails. This patch fixes the bug
by explicitly assigning -ENOMEM to err when kcalloc() returns a NULL
pointer.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/algif_skcipher.c

@@ -566,8 +566,10 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 			 * need to expand */
 			tmp = kcalloc(tx_nents * 2, sizeof(*tmp),
 				      GFP_KERNEL);
-			if (!tmp)
+			if (!tmp) {
+				err = -ENOMEM;
 				goto free;
+			}
 
 			sg_init_table(tmp, tx_nents * 2);
 			for (x = 0; x < tx_nents; x++)