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Bug #79828 Segfault when trying to access non-existing variable
Submitted: 2020-07-10 23:04 UTC Modified: 2020-07-13 07:55 UTC
From: sam at rmcreative dot ru Assigned: nikic (profile)
Status: Closed Package: Reproducible crash
PHP Version: 8.0.0alpha2 OS:
Private report: No CVE-ID: None
 [2020-07-10 23:04 UTC] sam at rmcreative dot ru
Executing test script under php:8.00-rc-cli-alpine segfaults.

Can also be seen at

Test script:
function getTime(): DateTimeInterface
    return $time;

echo __LINE__; // OK
getTime(); // Segfault
echo __LINE__; // We aren't getting here

Expected result:
Same output as PHP 7:

Notice: Undefined variable: time in /in/VRAoq on line 4

Fatal error: Uncaught TypeError: Return value of getTime() must implement interface DateTimeInterface, null returned in /in/VRAoq:4
Stack trace:
#0 /in/VRAoq(8): getTime()
#1 {main}
  thrown in /in/VRAoq on line 4

Process exited with code 255.

Actual result:
Process exited with code 139.


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 [2020-07-10 23:53 UTC]
-Status: Open +Status: Verified
 [2020-07-10 23:53 UTC]
Repro is returning an uninitialized variable inside a return-typed function.

function foo(): AnyType {
   return $uninitialized;

#0  0x0000000008696c3f in zend_get_executed_lineno () at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend_execute_API.c:560
#1  0x00000000086adcfc in get_filename_lineno (type=2, filename=0x7ffffffea6e8, lineno=0x7ffffffea6e4)
    at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend.c:1447
#2  0x00000000086adedd in zend_error (type=2, format=0x8f58527 "Undefined variable $%s") at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend.c:1483
#3  0x00000000086d8a9a in zval_undefined_cv (var=80) at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend_execute.c:269
#4  0x00000000086d8be6 in _get_zval_ptr_cv_BP_VAR_R (var=80) at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend_execute.c:342
#5  0x00000000087450c3 in ZEND_VERIFY_RETURN_TYPE_SPEC_CV_UNUSED_HANDLER () at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend_vm_execute.h:44554
#6  0x0000000008751842 in execute_ex (ex=0x7ffff4a13020) at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend_vm_execute.h:55746
#7  0x0000000008751db7 in zend_execute (op_array=0x7ffff4a5c280, return_value=0x0)
    at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend_vm_execute.h:56094
#8  0x00000000086aea0e in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/ubuntu/php/php-8.0.0alpha2-src/Zend/zend.c:1667
#9  0x0000000008617bdc in php_execute_script (primary_file=0x7ffffffed020) at /home/ubuntu/php/php-8.0.0alpha2-src/main/main.c:2537
#10 0x000000000879068f in do_cli (argc=2, argv=0x962c870) at /home/ubuntu/php/php-8.0.0alpha2-src/sapi/cli/php_cli.c:955
#11 0x0000000008791771 in main (argc=2, argv=0x962c870) at /home/ubuntu/php/php-8.0.0alpha2-src/sapi/cli/php_cli.c:1353

valgrind reports use of initialized value followed by an invalid read.
 [2020-07-13 07:55 UTC]
-Assigned To: +Assigned To: nikic
 [2020-07-13 08:05 UTC]
Automatic comment on behalf of
Log: Fixed bug #79828
 [2020-07-13 08:05 UTC]
-Status: Verified +Status: Closed
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