kern/parser: Fix resource leak if argc == 0

After processing the command-line yet arriving at the point where we are
setting argv, we are allocating memory, even if argc == 0, which makes
no sense since we never put anything into the allocated argv.

The solution is to simply return that we've successfully processed the
arguments but that argc == 0, and also ensure that argv is NULL when
we're not allocating anything in it.

There are only 2 callers of this function, and both are handling a zero
value in argc assuming nothing is allocated in argv.

Fixes: CID 96680

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/parser.c

@@ -146,6 +146,7 @@ grub_parser_split_cmdline (const char *cmdline,
   int i;
 
   *argc = 0;
+  *argv = NULL;
   do
     {
       if (!rd || !*rd)
@@ -207,6 +208,10 @@ grub_parser_split_cmdline (const char *cmdline,
       (*argc)++;
     }
 
+  /* If there are no args, then we're done. */
+  if (!*argc)
+    return 0;
+
   /* Reserve memory for the return values.  */
   args = grub_malloc (bp - buffer);
   if (!args)