Attachment 31514 Details for Bug 59600 – Compile and link with '-fsanitize=address -O2' and run to illustrate the bug

Compile and link with '-fsanitize=address -O2' and run to illustrate the bug

sanitize-bug.c (text/x-csrc), 1.14 KB, created by Paul Eggert on 2013-12-26 01:57:35 UTC

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Creator: Paul Eggert

Created: 2013-12-26 01:57:35 UTC

Size: 1.14 KB

patch

obsolete

>/* Compile with 'gcc -fsanitize=address -O2' and run; the program
>   crashes because when 'mark_memory' is inlined, the deference is
>   incorrectly sanitized.  Compiling with -DTHIS_WORKS_AROUND_THE_BUG
>   works around the bug.  */
>
>/* This is a simplified version of what Emacs does internally,
>   when marking its stack.  */
>
>static unsigned long sum;
>static void *stack_base;
>
>/* A simple substitute for what Emacs actually does.  */
>static void
>mark_maybe_pointer (void *p)
>{
>  sum ^= (unsigned long) p;
>}
>
>static void __attribute__ ((no_sanitize_address))
>#ifdef THIS_WORKS_AROUND_THE_BUG
>  __attribute__((noinline))
>#endif
>mark_memory (void **start, void **end)
>{
>  void **pp;
>
>  if (end < start)
>    {
>      void **tem = start;
>      start = end;
>      end = tem;
>    }
>
>  for (pp = start; pp < end; pp++)
>    {
>      /* This is the dereference that we don't want sanitized.  */
>      void *p = *pp;
>
>      mark_maybe_pointer (p);
>    }
>}
>
>static void
>mark_stack (void)
>{
>  void *end;
>  mark_memory (stack_base, &end);
>}
>
>void
>garbage_collect (void)
>{
>  mark_stack ();
>}
>
>int
>main (void)
>{
>  void *dummy;
>  stack_base = &dummy;
>  garbage_collect ();
>  return 0;
>}

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Attachments on bug 59600: 31514 | 31515 | 31516 | 31522