Bug #70089 [Opn]: segfault in PHP 7 at ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER ()

Edit report at https://bugs.php.net/bug.php?id=70089&edit=1 ID: 70089 User updated by: brian dot carpenter at gmail dot com Reported by: brian dot carpenter at gmail dot com Summary: segfault in PHP 7 at ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER () Status: Open Type: Bug Package: Reproducible crash Operating System: Debian 7 PHP Version: 7.0Git-2015-07-17 (Git) Block user comment: N Private report: N New Comment: Valgrind was delayed due to having to compile a new version to get an accurate read on things: ==4945== Invalid read of size 4 ==4945== at 0x1657B93: ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER (zend_vm_execute.h:16978) ==4945== by 0x15DC492: execute_ex (zend_vm_execute.h:406) ==4945== by 0x17FDEE4: zend_execute (zend_vm_execute.h:450) ==4945== by 0x141373B: zend_execute_scripts (zend.c:1399) ==4945== by 0x11BF18F: php_execute_script (main.c:2475) ==4945== by 0x1805678: do_cli (php_cli.c:971) ==4945== by 0x43E2F0: main (php_cli.c:1338) ==4945== Address 0x8 is not stack'd, malloc'd or (recently) free'd ==4945== ==4945== ==4945== Process terminating with default action of signal 11 (SIGSEGV) ==4945== Access not within mapped region at address 0x8 ==4945== at 0x1657B93: ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER (zend_vm_execute.h:16978) ==4945== by 0x15DC492: execute_ex (zend_vm_execute.h:406) ==4945== by 0x17FDEE4: zend_execute (zend_vm_execute.h:450) ==4945== by 0x141373B: zend_execute_scripts (zend.c:1399) ==4945== by 0x11BF18F: php_execute_script (main.c:2475) ==4945== by 0x1805678: do_cli (php_cli.c:971) ==4945== by 0x43E2F0: main (php_cli.c:1338) ==4945== If you believe this happened as a result of a stack ==4945== overflow in your program's main thread (unlikely but ==4945== possible), you can try to increase the size of the ==4945== main thread stack using the --main-stacksize= flag. ==4945== The main thread stack size used in this run was 8388608. Segmentation fault Previous Comments: ------------------------------------------------------------------------ [2015-07-17 05:14:32] brian dot carpenter at gmail dot com Description: ------------ While fuzzing PHP 7.0.0-dev (cli) (built: July 15 2015 16:00:56) with AFL (http://lcamtuf.coredump.cx/afl/), I found this script that segfaults at ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER (). Most likely a null ptr dereference. Test script: --------------- <?php $a=ptr00tr();[];function ptr00tr(){for(;;){$o=chr(0)[0][]=0;}} Expected result: ---------------- PHP 5.4.41-0+deb7u1 returns PHP Fatal error: Cannot use string offset as an array in test00-min on line 2. Actual result: -------------- Program received signal SIGSEGV, Segmentation fault. 0x0000000001657b93 in ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER () (gdb) bt #0 0x0000000001657b93 in ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER () #1 0x00000000015dc493 in execute_ex () #2 0x00000000017fdee5 in zend_execute () #3 0x000000000141373c in zend_execute_scripts () #4 0x00000000011bf190 in php_execute_script () #5 0x0000000001805679 in do_cli () at /home/geeknik/php-src/sapi/cli/php_cli.c:971 #6 0x000000000043e2f1 in main () at /home/geeknik/php-src/sapi/cli/php_cli.c:1338 (gdb) i r rax 0x0 0 rbx 0x7ffff6013130 140737320661296 rcx 0x1 1 rdx 0x7ffff60554c0 140737320932544 rsi 0x7ffff6013140 140737320661312 rdi 0x4 4 rbp 0x7fffffffcfa0 0x7fffffffcfa0 rsp 0x7fffffffa920 0x7fffffffa920 r8 0x1fd37c0 33372096 r9 0x80 128 r10 0x0 0 r11 0x0 0 r12 0x7ffff60020f0 140737320591600 r13 0x1fd4820 33376288 r14 0x7ffff60130c0 140737320661184 r15 0x7ffff6086220 140737321132576 rip 0x1657b93 0x1657b93 <ZEND_FETCH_DIM_W_SPEC_VAR_CONST_HANDLER+1267> eflags 0x10246 [ PF ZF IF RF ] cs 0x33 51 ss 0x2b 43 ds 0x0 0 es 0x0 0 fs 0x0 0 gs 0x0 0 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=70089&edit=1