Commit: Close memory leaks in chew

Commit: Close memory leaks in chew

[Nick Clifton]

Hi Guys,

  I have been trying to compile the binutils sources with address
  sanitization enabled and I have run into memory leaks in the chew
  program.  So I am checking in the patch below to fix them.

Cheers
  Nick

bfd/ChangeLog
2016-08-08  Nick Clifton  <nickc@redhat.com>

	* doc/chew.c (delete_string): Only free the string buffer if it is
	there.  Mark the buffer as NULL after freeing.
	(drop): Free the dropped string.
	(free_words): New function: Frees the memory allocated to the
	dictionary.
	(add_instrinsic): Duplicate the name string, so that it can be
	freed later on.
	(compile): Free unused words.
	(main): Free the dictionary and top level string buffers at the
	end.

diff --git a/bfd/doc/chew.c b/bfd/doc/chew.c
index 92b62cd..71c7e2d 100644
--- a/bfd/doc/chew.c
+++ b/bfd/doc/chew.c
@@ -170,7 +170,9 @@ static void
 delete_string (buffer)
      string_type *buffer;
 {
-  free (buffer->ptr);
+  if (buffer->ptr)
+    free (buffer->ptr);
+  buffer->ptr = NULL;
 }
 
 static char *
@@ -1088,6 +1090,7 @@ drop ()
 {
   tos--;
   check_range ();
+  delete_string (tos + 1);
   pc++;
 }
 
@@ -1244,6 +1247,35 @@ lookup_word (word)
 }
 
 static void
+free_words (void)
+{
+  dict_type *ptr = root;
+
+  while (ptr)
+    {
+      dict_type *next;
+
+      if (ptr->word)
+	free (ptr->word);
+      if (ptr->code)
+	{
+	  int i;
+	  for (i = 0; i < ptr->code_length; i ++)
+	    if (ptr->code[i] == push_text
+		&& ptr->code[i + 1])
+	      {
+		free (ptr->code[i + 1] - 1);
+		++ i;
+	      }
+	  free (ptr->code);
+	}
+      next = ptr->next;
+      free (ptr);
+      ptr = next;
+    }
+}
+
+static void
 perform ()
 {
   tos = stack;
@@ -1313,7 +1345,7 @@ add_intrinsic (name, func)
      char *name;
      void (*func) ();
 {
-  dict_type *new_d = newentry (name);
+  dict_type *new_d = newentry (strdup (name));
   add_to_definition (new_d, func);
   add_to_definition (new_d, 0);
 }
@@ -1334,24 +1366,27 @@ compile (string)
 {
   /* Add words to the dictionary.  */
   char *word;
+
   string = nextword (string, &word);
   while (string && *string && word[0])
     {
       if (strcmp (word, "var") == 0)
 	{
+	  free (word);
 	  string = nextword (string, &word);
-
 	  add_var (word);
 	  string = nextword (string, &word);
 	}
       else if (word[0] == ':')
 	{
 	  dict_type *ptr;
+
 	  /* Compile a word and add to dictionary.  */
+	  free (word);
 	  string = nextword (string, &word);
-
 	  ptr = newentry (word);
 	  string = nextword (string, &word);
+	  
 	  while (word[0] != ';')
 	    {
 	      switch (word[0])
@@ -1376,15 +1411,19 @@ compile (string)
 		     function */
 		  add_to_definition (ptr, push_number);
 		  add_to_definition (ptr, (stinst_type) atol (word));
+		  free (word);
 		  break;
 		default:
 		  add_to_definition (ptr, call);
 		  add_to_definition (ptr, (stinst_type) lookup_word (word));
+		  free (word);
 		}
 
 	      string = nextword (string, &word);
 	    }
 	  add_to_definition (ptr, 0);
+	  free (word);
+	  word = NULL;
 	  string = nextword (string, &word);
 	}
       else
@@ -1392,6 +1431,8 @@ compile (string)
 	  fprintf (stderr, "syntax error at %s\n", string - 1);
 	}
     }
+  if (word)
+    free (word);
 }
 
 static void
@@ -1575,6 +1616,9 @@ main (ac, av)
 	}
     }
   write_buffer (stack + 0, stdout);
+  free_words ();
+  delete_string (&pptr);
+  delete_string (&buffer);
   if (tos != stack)
     {
       fprintf (stderr, "finishing with current stack level %ld\n",

Re: Commit: Close memory leaks in chew

[Andreas Schwab]

On Mo, Aug 08 2016, Nick Clifton <nickc@redhat.com> wrote:

> diff --git a/bfd/doc/chew.c b/bfd/doc/chew.c
> index 92b62cd..71c7e2d 100644
> --- a/bfd/doc/chew.c
> +++ b/bfd/doc/chew.c
> @@ -170,7 +170,9 @@ static void
>  delete_string (buffer)
>       string_type *buffer;
>  {
> -  free (buffer->ptr);
> +  if (buffer->ptr)
> +    free (buffer->ptr);

free (0) is a no-op.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: Commit: Close memory leaks in chew

[Nick Clifton]

Hi Andreas,

>> -  free (buffer->ptr);
>> +  if (buffer->ptr)
>> +    free (buffer->ptr);
> 
> free (0) is a no-op.

OK - I will remember that for the future.  I doubt if it really matters
here, since the performance penalty of the test is trivial.

Cheers
  Nick