nobu	2013-05-17 11:07:00 +0900 (Fri, 17 May 2013)

  New Revision: 40791

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=40791

  Log:
    eval_intern.h: jmpbuf must be accessible
    
    * eval_intern.h (TH_PUSH_TAG): ensure jmpbuf to be accessible before
      pushing tag to get rid of unaccessible tag by stack overflow.

  Modified files:
    trunk/ChangeLog
    trunk/eval_intern.h

Index: eval_intern.h
===================================================================
--- eval_intern.h	(revision 40790)
+++ eval_intern.h	(revision 40791)
@@ -91,9 +91,20 @@ extern int select_large_fdset(int, fd_se https://github.com/ruby/ruby/blob/trunk/eval_intern.h#L91
       rb_fiber_start(); \
   } while (0)
 
+/*
+  ensure tag to be accessible, `buf' is at the beginning.
+  the end is `prev' which is written in TH_PUSH_TAG().
+*/
+#if defined(__GNUC__) && __GNUC__ >= 4
+/* suppress -Wstrict-aliasing, and should be inlined */
+# define ENSURE_TAG_WRITABLE(tag) MEMZERO((tag).buf, int, 1)
+#else
+# define ENSURE_TAG_WRITABLE(tag) (*(volatile int *)(tag).buf = 0)
+#endif
 #define TH_PUSH_TAG(th) do { \
   rb_thread_t * const _th = (th); \
   struct rb_vm_tag _tag; \
+  ENSURE_TAG_WRITABLE(_tag); \
   _tag.tag = 0; \
   _tag.prev = _th->tag; \
   _th->tag = &_tag;
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 40790)
+++ ChangeLog	(revision 40791)
@@ -1,3 +1,8 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Fri May 17 11:06:48 2013  Nobuyoshi Nakada  <nobu@r...>
+
+	* eval_intern.h (TH_PUSH_TAG): ensure jmpbuf to be accessible before
+	  pushing tag to get rid of unaccessible tag by stack overflow.
+
 Thu May 16 17:15:32 2013  NARUSE, Yui  <naruse@r...>
 
 	* vm_eval.c (rb_catch_obj): add volatile to tag to prevent crash

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