Segfault caused by a derefernce of a high value address

[YuanchengJiang]

Description

The following code:

<?php
ob_start();
echo "*** Testing session_decode() : error functionality ***\n";
$data = "foo|a:3:{i:0;i:1;i:1;i:2;i:2;i:3;}guff|R:1;blah|R:1;";
for($index = 0; $index < strlen($data); $index++) {
    if(session_status() != PHP_SESSION_ACTIVE) { session_start(); }
    echo "\n-- Iteration $index --\n";
    $encoded = substr($data, 0, $index);
    var_dump(session_decode($encoded));
    var_dump($_SESSION);
};

$file_c = __DIR__ . "file_does_not_exist1";
$file_p = __DIR__ . "file_does_not_exist2";
file_put_contents($file_c, "<?php require '$file_p'; class c extends p {} ?>");
file_put_contents($file_p, '<?php class p { protected $var = ""; } ?>');
require $file_c;
$a = new c();
require $file_c;
?>

Resulted in this output: (asan enabled)

Segmentation fault (core dumped)

or

==1523719==ERROR: AddressSanitizer: SEGV on unknown address (pc 0x7f28d5b0b31e bp 0x65f9f2bee1cf8551 sp 0xece1f2bee1a4f502 T0)
==1523719==The signal is caused by a READ memory access.
==1523719==Hint: this fault was caused by a dereference of a high value address (see register values below).  Disassemble the provided pc to learn which register was used.
AddressSanitizer:DEADLYSIGNAL

PHP Version

PHP 8.4.0-dev

Operating System

ubuntu 22.04

[devnexen]

can reproduce all the way back to 8.2 and with debug builds, occurring within the execution context (ie zend_try) but would need a much better look to see what s really going on. I won t have time to do so until later today.

[ndossche]

This is a duplicate of #13680
Fixed by the PR linked in that issue.