mmap.c (backtrace_vector_release): Make sure freed block is aligned on 8-byte boundary.

	* mmap.c (backtrace_vector_release): Make sure freed block is
	aligned on 8-byte boundary.

From-SVN: r192945

libbacktrace/ChangeLog

+2012-10-29  Ian Lance Taylor  <iant@google.com>
+
+	* mmap.c (backtrace_vector_release): Make sure freed block is
+	aligned on 8-byte boundary.
+
 2012-10-26  Ian Lance Taylor  <iant@google.com>
 
 	PR other/55087

libbacktrace/mmap.c

@@ -229,8 +229,18 @@ backtrace_vector_release (struct backtrace_state *state,
 			  backtrace_error_callback error_callback,
 			  void *data)
 {
-  backtrace_free (state, (char *) vec->base + vec->size, vec->alc,
-		  error_callback, data);
+  size_t size;
+  size_t alc;
+  size_t aligned;
+
+  /* Make sure that the block that we free is aligned on an 8-byte
+     boundary.  */
+  size = vec->size;
+  alc = vec->alc;
+  aligned = (size + 7) & ~ (size_t) 7;
+  alc -= aligned - size;
+
+  backtrace_free (state, (char *) vec->base + size, alc, error_callback, data);
   vec->alc = 0;
   return 1;
 }