Merge lp:~vlad-lesin/percona-server/5.6-bug-1351148 into lp:percona-server/5.6

[Vlad Lesin]

Bug #1351128 fix.

  The bug's summary:

  1) The value in pins->stack_ends_here is actually incorrect. This value is
  calculated when the thread is initialized in my_thread_init(). The problem is
  that the value doesn't take into account existing stack usage and just adds the
  thread stack size to calculate the beginning of the stack.

  2) _lf_pinbox_real_free() is using alloca() in a very unsafe way. alloca()
  should only be used by leaf functions, since you cannot predict the amount of
  stack space that non-leaf functions will use. As pins->stack_ends_here is
  calculated in wrong way and there is no window for the qsort() which is invoked
  from _lf_pinbox_real_free() after alloca(), stack overflow can take place.

  The solution:

  1) Take into accout the current stack offset when stack size is calculated
  in my_thread_init();

  2) Don't allocate the whole free stack space in _lf_pinbox_real_free(),
  take some window for qsort();

http://jenkins.percona.com/view/PS%205.6/job/percona-server-5.6-param/714/

[Laurynas Biveinis (laurynas-biveinis)]

review: Needs Fixing

[Laurynas Biveinis (laurynas-biveinis)]

5.6 not merged from the last 5.5 push?

review: Needs Fixing

[Vlad Lesin (vlad-lesin)]

> 5.6 not merged from the last 5.5 push?

It looks like I forgot to push the last version. Have just pushed.

[Laurynas Biveinis (laurynas-biveinis)]

review: Approve

=== modified file 'mysys/lf_alloc-pin.c'
--- mysys/lf_alloc-pin.c	2014-12-01 07:53:48 +0000
+++ mysys/lf_alloc-pin.c	2014-12-02 14:03:08 +0000
@@ -105,6 +105,13 @@
 
 #define LF_PINBOX_MAX_PINS 65536
 
+/*
+  When allocation on stack happens leave this
+  amount of stack memory for further functions
+  call.
+*/
+#define LF_PINBOX_EXTRA_STACK_SPACE  8192
+
 static void _lf_pinbox_real_free(LF_PINS *pins);
 
 /*
@@ -349,7 +356,9 @@
   {
     int alloca_size= sizeof(void *)*LF_PINBOX_PINS*npins;
     /* create a sorted list of pinned addresses, to speed up searches */
-    if (available_stack_size(&pinbox, *pins->stack_ends_here) > alloca_size)
+    if (available_stack_size(&pinbox, *pins->stack_ends_here) >
+        /* leave LF_PINBOX_EXTRA_STACK_SPACE bytes for qsort() call */
+        (alloca_size + LF_PINBOX_EXTRA_STACK_SPACE))
     {
       struct st_harvester hv;
       addr= (void **) alloca(alloca_size);
 
=== modified file 'mysys/my_thr_init.c'
--- mysys/my_thr_init.c	2014-12-01 07:53:48 +0000
+++ mysys/my_thr_init.c	2014-12-02 14:03:08 +0000
@@ -297,8 +297,34 @@
   mysql_mutex_init(key_my_thread_var_mutex, &tmp->mutex, MY_MUTEX_INIT_FAST);
   mysql_cond_init(key_my_thread_var_suspend, &tmp->suspend, NULL);
 
-  tmp->stack_ends_here= (char*)&tmp +
-                         STACK_DIRECTION * (long)my_thread_stack_size;
+#if defined(_GNU_SOURCE) && (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
+  {
+    pthread_attr_t attr;
+    char*          stack_addr;
+    size_t         stack_size;
+
+    if (pthread_attr_init(&attr) ||
+        pthread_getattr_np(tmp->pthread_self, &attr) ||
+        pthread_attr_getstack(&attr, (void**)&stack_addr, &stack_size))
+    {
+      error= 1;
+      goto end;
+    }
+    tmp->stack_ends_here= stack_addr;
+
+    if (pthread_attr_destroy(&attr))
+    {
+      error= 1;
+      goto end;
+    }
+  }
+#else  //defined(_GNU_SOURCE) && (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
+  /* assuming tmp is located within the first page of the stack */
+  tmp->stack_ends_here= (void **)(((long long)&tmp & (~((long long)my_getpagesize() - 1))) +
+                                  ((STACK_DIRECTION == 1) ?
+                                  my_thread_stack_size :
+                                  my_getpagesize() - my_thread_stack_size));
+#endif //defined(_GNU_SOURCE) && (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
 
   mysql_mutex_lock(&THR_LOCK_threads);
   tmp->id= ++thread_id;