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Bug #71843 null ptr deref ZEND_RETURN_SPEC_CONST_HANDLER (zend_vm_execute.h:3479)
Submitted: 2016-03-17 09:16 UTC Modified: 2016-03-17 10:30 UTC
From: brian dot carpenter at gmail dot com Assigned: laruence
Status: Closed Package: Reproducible crash
PHP Version: 7.0Git-2016-03-17 (Git) OS: Debian 8.2 x64
Private report: No CVE-ID:
 [2016-03-17 09:16 UTC] brian dot carpenter at gmail dot com
Description:
------------
While fuzzing PHP 7.1.0-dev (cli) (built: Mar 16 2016 17:03:41) with American Fuzzy Lop, I encountered a null pointer dereference and segfault. 

Test script:
---------------
<?0&~e&~r;6&&~_?>

Expected result:
----------------
No crash.

Actual result:
--------------
geeknik@debian:~/php-tmp/out/4/crashes$ valgrind -q ~/php-src/sapi/cli/php test01
==55572== Invalid write of size 8
==55572==    at 0x1877A42: ZEND_RETURN_SPEC_CONST_HANDLER (zend_vm_execute.h:3479)
==55572==    by 0x1615532: execute_ex (zend_vm_execute.h:423)
==55572==    by 0x187F654: zend_execute (zend_vm_execute.h:467)
==55572==    by 0x14520D7: zend_execute_scripts (zend.c:1427)
==55572==    by 0x11FFE8F: php_execute_script (main.c:2487)
==55572==    by 0x18888E4: do_cli (php_cli.c:974)
==55572==    by 0x4507F0: main (php_cli.c:1344)
==55572==  Address 0x3 is not stack'd, malloc'd or (recently) free'd
==55572== 
==55572== 
==55572== Process terminating with default action of signal 11 (SIGSEGV)
==55572==  Access not within mapped region at address 0x3
==55572==    at 0x1877A42: ZEND_RETURN_SPEC_CONST_HANDLER (zend_vm_execute.h:3479)
==55572==    by 0x1615532: execute_ex (zend_vm_execute.h:423)
==55572==    by 0x187F654: zend_execute (zend_vm_execute.h:467)
==55572==    by 0x14520D7: zend_execute_scripts (zend.c:1427)
==55572==    by 0x11FFE8F: php_execute_script (main.c:2487)
==55572==    by 0x18888E4: do_cli (php_cli.c:974)
==55572==    by 0x4507F0: main (php_cli.c:1344)
==55572==  If you believe this happened as a result of a stack
==55572==  overflow in your program's main thread (unlikely but
==55572==  possible), you can try to increase the size of the
==55572==  main thread stack using the --main-stacksize= flag.
==55572==  The main thread stack size used in this run was 8388608.
Segmentation fault

(gdb) r test01
Starting program: /home/geeknik/php-src/sapi/cli/php test01
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x0000000001877a42 in ZEND_RETURN_SPEC_CONST_HANDLER () at /home/geeknik/php-src/Zend/zend_vm_execute.h:3479
3479				ZVAL_COPY_VALUE(EX(return_value), retval_ptr);
(gdb) bt
#0  0x0000000001877a42 in ZEND_RETURN_SPEC_CONST_HANDLER () at /home/geeknik/php-src/Zend/zend_vm_execute.h:3479
#1  0x0000000001615533 in execute_ex (ex=<optimized out>) at /home/geeknik/php-src/Zend/zend_vm_execute.h:423
#2  0x000000000187f655 in zend_execute (op_array=op_array@entry=0x7ffff6085140, return_value=return_value@entry=0x0)
    at /home/geeknik/php-src/Zend/zend_vm_execute.h:467
#3  0x00000000014520d8 in zend_execute_scripts (type=type@entry=8, retval=retval@entry=0x0, file_count=-167694288, file_count@entry=3)
    at /home/geeknik/php-src/Zend/zend.c:1427
#4  0x00000000011ffe90 in php_execute_script (primary_file=0x7fffffffcf10) at /home/geeknik/php-src/main/main.c:2487
#5  0x00000000018888e5 in do_cli (argc=4, argv=0x1) at /home/geeknik/php-src/sapi/cli/php_cli.c:974
#6  0x00000000004507f1 in main (argc=4, argv=0x1) at /home/geeknik/php-src/sapi/cli/php_cli.c:1344
(gdb) list
3474					zval_dtor_func_for_ptr(Z_COUNTED_P(free_op1));
3475				}
3476			}
3477		} else {
3478			if ((IS_CONST & (IS_CONST|IS_TMP_VAR))) {
3479				ZVAL_COPY_VALUE(EX(return_value), retval_ptr);
3480				if (IS_CONST == IS_CONST) {
3481					if (UNEXPECTED(Z_OPT_COPYABLE_P(EX(return_value)))) {
3482						zval_copy_ctor_func(EX(return_value));
3483					}

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 [2016-03-17 10:30 UTC] laruence@php.net
-Assigned To: +Assigned To: laruence
 [2016-03-17 10:30 UTC] laruence@php.net
actually, this also have problems in 5.6

which could be fixed by :

diff --git a/ext/opcache/Optimizer/block_pass.c b/ext/opcache/Optimizer/block_pass.c
index c146d0c..bf3f144 100644
--- a/ext/opcache/Optimizer/block_pass.c
+++ b/ext/opcache/Optimizer/block_pass.c
@@ -716,8 +716,11 @@ static void zend_optimize_block(zend_code_block *block, zend_op_array *op_array,
                        if (src->opcode == ZEND_BOOL) {
                                if (ZEND_OP1_TYPE(src) == IS_CONST) {
                                        literal_dtor(&ZEND_OP1_LITERAL(src));
+                         } else if (ZEND_OP1_TYPE(src) == IS_TMP_VAR) {
+                                 src->opcode = ZEND_FREE;
+                         } else {
+                                 MAKE_NOP(src);
                                }
-                           MAKE_NOP(src);
                                MAKE_NOP(opline);
                        }
                }

thanks
 [2016-03-17 13:26 UTC] laruence@php.net
Automatic comment on behalf of laruence@gmail.com
Revision: http://git.php.net/?p=php-src.git;a=commit;h=8e2f658f49c76c9feed894414fb3a8edb27beef0
Log: Fixed bug #71843 (null ptr deref ZEND_RETURN_SPEC_CONST_HANDLER)
 [2016-03-17 13:26 UTC] laruence@php.net
-Status: Assigned +Status: Closed
 [2016-03-17 13:28 UTC] laruence@php.net
Automatic comment on behalf of laruence@gmail.com
Revision: http://git.php.net/?p=php-src.git;a=commit;h=8e2f658f49c76c9feed894414fb3a8edb27beef0
Log: Fixed bug #71843 (null ptr deref ZEND_RETURN_SPEC_CONST_HANDLER)
 
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