lib/legacy_parse: Add missing grub_malloc() failure check

This patch adds a NULL check after grub_malloc() call. Missing a failure
check after calling grub_malloc() can lead to undefined behavior. If the
allocation fails and returns NULL subsequent dereferencing or writing to
the pointer will likely result in a runtime error such as a segmentation
fault.

Signed-off-by: Avnish Chouhan <avnish@linux.ibm.com>
Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/lib/legacy_parse.c

@@ -508,6 +508,9 @@ grub_legacy_parse (const char *buf, char **entryname, char **suffix)
       char *ret;
       int len = grub_strlen (buf);
       ret = grub_malloc (len + 2);
+      if (ret == NULL)
+        return NULL;
+
       grub_memcpy (ret, buf, len);
       if (len && ret[len - 1] == '\n')
 	ret[len] = 0;