[Bug 577710] Re: php5 crashed with SIGSEGV in execute()

Clint Byrum clint at fewbar.com
Tue Sep 14 01:28:43 BST 2010 

Vladimir, thanks very much for this bug report!

I believe this is essentially infinite recursion caused by the way PHP
resolves methods..

the test case basically does this

create a new Test_PHP5 object, named $this
call $this->__construct()
$this->__construct calls parent::Test(), which leaves $this as a Test_PHP5, and maps to Test::Test()
Test::Test() calls $this->__construct(), which is mapped to Test_PHP5::__construct()
$this->__construct() calls parent::Test() which maps to Test::Test()
... infinite recursion

This would cause issues with any PHP interpreter. On Maverick though,
this is the result:


PHP Fatal error:  Maximum function nesting level of '100' reached, aborting! in /home/clint/test.php on line 7
PHP Stack trace:
PHP   1. {main}() /home/clint/test.php:0
PHP   2. Test_PHP5->__construct() /home/clint/test.php:26
PHP   3. Test->Test() /home/clint/test.php:22
PHP   4. Test_PHP5->__construct() /home/clint/test.php:7
PHP   5. Test->Test() /home/clint/test.php:22
PHP   6. Test_PHP5->__construct() /home/clint/test.php:7
PHP   7. Test->Test() /home/clint/test.php:22
PHP   8. Test_PHP5->__construct() /home/clint/test.php:7
PHP   9. Test->Test() /home/clint/test.php:22
PHP  10. Test_PHP5->__construct() /home/clint/test.php:7
PHP  11. Test->Test() /home/clint/test.php:22
PHP  12. Test_PHP5->__construct() /home/clint/test.php:7
PHP  13. Test->Test() /home/clint/test.php:22
PHP  14. Test_PHP5->__construct() /home/clint/test.php:7
PHP  15. Test->Test() /home/clint/test.php:22
PHP  16. Test_PHP5->__construct() /home/clint/test.php:7
PHP  17. Test->Test() /home/clint/test.php:22
PHP  18. Test_PHP5->__construct() /home/clint/test.php:7
PHP  19. Test->Test() /home/clint/test.php:22
PHP  20. Test_PHP5->__construct() /home/clint/test.php:7
PHP  21. Test->Test() /home/clint/test.php:22
PHP  22. Test_PHP5->__construct() /home/clint/test.php:7
PHP  23. Test->Test() /home/clint/test.php:22
PHP  24. Test_PHP5->__construct() /home/clint/test.php:7
PHP  25. Test->Test() /home/clint/test.php:22
PHP  26. Test_PHP5->__construct() /home/clint/test.php:7
PHP  27. Test->Test() /home/clint/test.php:22
PHP  28. Test_PHP5->__construct() /home/clint/test.php:7
PHP  29. Test->Test() /home/clint/test.php:22
PHP  30. Test_PHP5->__construct() /home/clint/test.php:7
PHP  31. Test->Test() /home/clint/test.php:22
PHP  32. Test_PHP5->__construct() /home/clint/test.php:7
PHP  33. Test->Test() /home/clint/test.php:22
PHP  34. Test_PHP5->__construct() /home/clint/test.php:7
PHP  35. Test->Test() /home/clint/test.php:22
PHP  36. Test_PHP5->__construct() /home/clint/test.php:7
PHP  37. Test->Test() /home/clint/test.php:22
PHP  38. Test_PHP5->__construct() /home/clint/test.php:7
PHP  39. Test->Test() /home/clint/test.php:22
PHP  40. Test_PHP5->__construct() /home/clint/test.php:7
PHP  41. Test->Test() /home/clint/test.php:22
PHP  42. Test_PHP5->__construct() /home/clint/test.php:7
PHP  43. Test->Test() /home/clint/test.php:22
PHP  44. Test_PHP5->__construct() /home/clint/test.php:7
PHP  45. Test->Test() /home/clint/test.php:22
PHP  46. Test_PHP5->__construct() /home/clint/test.php:7
PHP  47. Test->Test() /home/clint/test.php:22
PHP  48. Test_PHP5->__construct() /home/clint/test.php:7
PHP  49. Test->Test() /home/clint/test.php:22
PHP  50. Test_PHP5->__construct() /home/clint/test.php:7
PHP  51. Test->Test() /home/clint/test.php:22
PHP  52. Test_PHP5->__construct() /home/clint/test.php:7
PHP  53. Test->Test() /home/clint/test.php:22
PHP  54. Test_PHP5->__construct() /home/clint/test.php:7
PHP  55. Test->Test() /home/clint/test.php:22
PHP  56. Test_PHP5->__construct() /home/clint/test.php:7
PHP  57. Test->Test() /home/clint/test.php:22
PHP  58. Test_PHP5->__construct() /home/clint/test.php:7
PHP  59. Test->Test() /home/clint/test.php:22
PHP  60. Test_PHP5->__construct() /home/clint/test.php:7
PHP  61. Test->Test() /home/clint/test.php:22
PHP  62. Test_PHP5->__construct() /home/clint/test.php:7
PHP  63. Test->Test() /home/clint/test.php:22
PHP  64. Test_PHP5->__construct() /home/clint/test.php:7
PHP  65. Test->Test() /home/clint/test.php:22
PHP  66. Test_PHP5->__construct() /home/clint/test.php:7
PHP  67. Test->Test() /home/clint/test.php:22
PHP  68. Test_PHP5->__construct() /home/clint/test.php:7
PHP  69. Test->Test() /home/clint/test.php:22
PHP  70. Test_PHP5->__construct() /home/clint/test.php:7
PHP  71. Test->Test() /home/clint/test.php:22
PHP  72. Test_PHP5->__construct() /home/clint/test.php:7
PHP  73. Test->Test() /home/clint/test.php:22
PHP  74. Test_PHP5->__construct() /home/clint/test.php:7
PHP  75. Test->Test() /home/clint/test.php:22
PHP  76. Test_PHP5->__construct() /home/clint/test.php:7
PHP  77. Test->Test() /home/clint/test.php:22
PHP  78. Test_PHP5->__construct() /home/clint/test.php:7
PHP  79. Test->Test() /home/clint/test.php:22
PHP  80. Test_PHP5->__construct() /home/clint/test.php:7
PHP  81. Test->Test() /home/clint/test.php:22
PHP  82. Test_PHP5->__construct() /home/clint/test.php:7
PHP  83. Test->Test() /home/clint/test.php:22
PHP  84. Test_PHP5->__construct() /home/clint/test.php:7
PHP  85. Test->Test() /home/clint/test.php:22
PHP  86. Test_PHP5->__construct() /home/clint/test.php:7
PHP  87. Test->Test() /home/clint/test.php:22
PHP  88. Test_PHP5->__construct() /home/clint/test.php:7
PHP  89. Test->Test() /home/clint/test.php:22
PHP  90. Test_PHP5->__construct() /home/clint/test.php:7
PHP  91. Test->Test() /home/clint/test.php:22
PHP  92. Test_PHP5->__construct() /home/clint/test.php:7
PHP  93. Test->Test() /home/clint/test.php:22
PHP  94. Test_PHP5->__construct() /home/clint/test.php:7
PHP  95. Test->Test() /home/clint/test.php:22
PHP  96. Test_PHP5->__construct() /home/clint/test.php:7
PHP  97. Test->Test() /home/clint/test.php:22
PHP  98. Test_PHP5->__construct() /home/clint/test.php:7
PHP  99. Test->Test() /home/clint/test.php:22

As you can see, Test::__construct() is never called.

When I run your test script on lucid with the latest updates, it
actually just sits there and doesn't return anything, nor does it
segfault.

As far as I know, you can't really access overriden methods from the
parent itself, you have to call parent::methodname from the overriding
method to get to that old code. Given the situation above, the right way
to solve this problem is not to call parent::Test(), but
parent::__construct().

I'm going to close this report as invalid, but please feel free to re-
open it (set it to New) if you feel that I have misunderstood the intent
of the test case or if you have a different test case that shows the
crash without overloading the stack.

** Changed in: php5 (Ubuntu)
       Status: Triaged => Invalid

-- 
php5 crashed with SIGSEGV in execute()
https://bugs.launchpad.net/bugs/577710
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