RAND_write_file(): Avoid potential file descriptor leak

If fdopen() call fails we need to close the fd. Also
return early as this is most likely some fatal error.

Fixes openssl#25064

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from openssl#25081)

crypto/rand/randfile.c

@@ -208,8 +208,16 @@ int RAND_write_file(const char *file)
          * should be restrictive from the start
          */
         int fd = open(file, O_WRONLY | O_CREAT | O_BINARY, 0600);
-        if (fd != -1)
+
+        if (fd != -1) {
             out = fdopen(fd, "wb");
+            if (out == NULL) {
+                close(fd);
+                ERR_raise_data(ERR_LIB_RAND, RAND_R_CANNOT_OPEN_FILE,
+                               "Filename=%s", file);
+                return -1;
+            }
+        }
     }
 #endif