pkcs7: return correct error code if pkcs7_check_authattrs() fails

If pkcs7_check_authattrs() returns an error code, we should pass that
error code on, rather than using ENOMEM.

Fixes: 99db44350672 ("PKCS#7: Appropriately restrict authenticated attributes and content type")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>

crypto/asymmetric_keys/pkcs7_parser.c

@@ -148,8 +148,10 @@ struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
 	}
 
 	ret = pkcs7_check_authattrs(ctx->msg);
-	if (ret < 0)
+	if (ret < 0) {
+		msg = ERR_PTR(ret);
 		goto out;
+	}
 
 	msg = ctx->msg;
 	ctx->msg = NULL;