crypto: algif_hash - wait for crypto_ahash_init() to complete

commit fe097861 upstream.

hash_sendmsg/sendpage() need to wait for the completion
of crypto_ahash_init() otherwise it can cause panic.
Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

crypto/algif_hash.c

@@ -56,7 +56,8 @@ static int hash_sendmsg(struct kiocb *unused, struct socket *sock,
 
 	lock_sock(sk);
 	if (!ctx->more) {
-		err = crypto_ahash_init(&ctx->req);
+		err = af_alg_wait_for_completion(crypto_ahash_init(&ctx->req),
+						&ctx->completion);
 		if (err)
 			goto unlock;
 	}
@@ -136,6 +137,7 @@ static ssize_t hash_sendpage(struct socket *sock, struct page *page,
 	} else {
 		if (!ctx->more) {
 			err = crypto_ahash_init(&ctx->req);
+			err = af_alg_wait_for_completion(err, &ctx->completion);
 			if (err)
 				goto unlock;
 		}