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Bug #73356 crash in bzcompress function
Submitted: 2016-10-20 13:48 UTC Modified: 2017-02-13 01:06 UTC
From: nguyenluan dot vnn at gmail dot com Assigned: stas (profile)
Status: Closed Package: Bzip2 Related
PHP Version: 5.6.27 OS:
Private report: No CVE-ID: None
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 [2016-10-20 13:48 UTC] nguyenluan dot vnn at gmail dot com
bzcompress function could output string larger than 2Gb when compressing string with high entropy.

Test script:
    ini_set('memory_limit', -1);
    $str = openssl_random_pseudo_bytes(0x7fffffff);  // (1) generate high entropy string
    $str1 = bzcompress($str, 1);                     // (2) lowest compression level

Expected result:
No crash. No string return since output is larger than 2Gb.

Actual result:
gdb-peda$ r ../test/string/test_bzcompress.php 
Starting program: /home/user/Desktop/php-5.6.27/sapi/cli/php ../test/string/test_bzcompress.php
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/".
int(-2130227446)  // (2) string larger than 2Gb

Program received signal SIGSEGV, Segmentation fault.

RAX: 0x7ffe6bc2ef7a 
RBX: 0x0 
RCX: 0x10c4db8 ("/home/user/Desktop/php-5.6.27/Zend/zend_execute.h")
RDX: 0x7ffeeabba070 ("BZh11AY&SYǥÈ")
RSI: 0x10c4db8 ("/home/user/Desktop/php-5.6.27/Zend/zend_execute.h")
RDI: 0x7ffff7fb94c0 --> 0x7ffeeabba070 ("BZh11AY&SYǥÈ")
RBP: 0x7fffffffb9b0 --> 0x7fffffffb9e0 --> 0x7fffffffba10 --> 0x7fffffffba40 --> 0x7fffffffba60 --> 0x7fffffffba80 (--> ...)
RSP: 0x7fffffffb990 --> 0x7 
RIP: 0xa981a0 (<_zval_dtor_func+99>:	movzx  eax,BYTE PTR [rax])
R8 : 0x136 
R9 : 0x10c4db8 ("/home/user/Desktop/php-5.6.27/Zend/zend_execute.h")
R10: 0x86f 
R11: 0x7ffff380f730 --> 0xfffda400fffda12f 
R12: 0x443a90 (<_start>:	xor    ebp,ebp)
R13: 0x7fffffffe1a0 --> 0x2 
R14: 0x0 
R15: 0x0
EFLAGS: 0x10203 (CARRY parity adjust zero sign trap INTERRUPT direction overflow)
   0xa98198 <_zval_dtor_func+91>:	mov    eax,DWORD PTR [rax+0x8]
   0xa9819b <_zval_dtor_func+94>:	cdqe   
   0xa9819d <_zval_dtor_func+96>:	add    rax,rdx
=> 0xa981a0 <_zval_dtor_func+99>:	movzx  eax,BYTE PTR [rax]
   0xa981a3 <_zval_dtor_func+102>:	test   al,al
   0xa981a5 <_zval_dtor_func+104>:	je     0xa981d4 <_zval_dtor_func+151>
   0xa981a7 <_zval_dtor_func+106>:	mov    rax,QWORD PTR [rbp-0x8]
   0xa981ab <_zval_dtor_func+110>:	mov    rax,QWORD PTR [rax]
0000| 0x7fffffffb990 --> 0x7 
0008| 0x7fffffffb998 --> 0x4ff7f863f8 
0016| 0x7fffffffb9a0 --> 0x10c4db8 ("/home/user/Desktop/php-5.6.27/Zend/zend_execute.h")
0024| 0x7fffffffb9a8 --> 0x7ffff7fb94c0 --> 0x7ffeeabba070 ("BZh11AY&SYǥÈ")
0032| 0x7fffffffb9b0 --> 0x7fffffffb9e0 --> 0x7fffffffba10 --> 0x7fffffffba40 --> 0x7fffffffba60 --> 0x7fffffffba80 (--> ...)
0040| 0x7fffffffb9b8 --> 0xa830ef (<_zval_dtor+53>:	jmp    0xa830f2 <_zval_dtor+56>)
0048| 0x7fffffffb9c0 ("/usr/local/lO")
0056| 0x7fffffffb9c8 --> 0x4f6c2f6c61 ('al/lO')
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x0000000000a981a0 in _zval_dtor_func (zvalue=0x7ffff7fb94c0, 
    __zend_filename=0x10c4db8 "/home/user/Desktop/php-5.6.27/Zend/zend_execute.h", __zend_lineno=0x4f)
    at /home/user/Desktop/php-5.6.27/Zend/zend_variables.c:36
36				CHECK_ZVAL_STRING_REL(zvalue);

gdb-peda$ bt
#0  0x0000000000a981a0 in _zval_dtor_func (zvalue=0x7ffff7fb94c0, 
    __zend_filename=0x10c4db8 "/home/user/Desktop/php-5.6.27/Zend/zend_execute.h", __zend_lineno=0x4f)
    at /home/user/Desktop/php-5.6.27/Zend/zend_variables.c:36
#1  0x0000000000a830ef in _zval_dtor (zvalue=0x7ffff7fb94c0, 
    __zend_filename=0x10c4db8 "/home/user/Desktop/php-5.6.27/Zend/zend_execute.h", __zend_lineno=0x4f)
    at /home/user/Desktop/php-5.6.27/Zend/zend_variables.h:35
#2  0x0000000000a831ba in i_zval_ptr_dtor (zval_ptr=0x7ffff7fb94c0, 
    __zend_filename=0x10c70a0 "/home/user/Desktop/php-5.6.27/Zend/zend_variables.c", __zend_lineno=0xbc)
    at /home/user/Desktop/php-5.6.27/Zend/zend_execute.h:79
#3  0x0000000000a84493 in _zval_ptr_dtor (zval_ptr=0x7ffff7fbad88, 
    __zend_filename=0x10c70a0 "/home/user/Desktop/php-5.6.27/Zend/zend_variables.c", __zend_lineno=0xbc)
    at /home/user/Desktop/php-5.6.27/Zend/zend_execute_API.c:424
#4  0x0000000000a9870b in _zval_ptr_dtor_wrapper (zval_ptr=0x7ffff7fbad88)
    at /home/user/Desktop/php-5.6.27/Zend/zend_variables.c:188
#5  0x0000000000aad5db in i_zend_hash_bucket_delete (
    ht=0x1457708 <executor_globals+360>, p=0x7ffff7fbad70)
    at /home/user/Desktop/php-5.6.27/Zend/zend_hash.c:182
#6  0x0000000000aad6b3 in zend_hash_bucket_delete (
    ht=0x1457708 <executor_globals+360>, p=0x7ffff7fbad70)
    at /home/user/Desktop/php-5.6.27/Zend/zend_hash.c:192
#7  0x0000000000aaf3c6 in zend_hash_graceful_reverse_destroy (
    ht=0x1457708 <executor_globals+360>)
    at /home/user/Desktop/php-5.6.27/Zend/zend_hash.c:613
#8  0x0000000000a83c8f in shutdown_executor ()
    at /home/user/Desktop/php-5.6.27/Zend/zend_execute_API.c:244
#9  0x0000000000a9aa59 in zend_deactivate ()
    at /home/user/Desktop/php-5.6.27/Zend/zend.c:960
#10 0x00000000009fbb34 in php_request_shutdown (dummy=0x0)
    at /home/user/Desktop/php-5.6.27/main/main.c:1899
#11 0x0000000000b59806 in do_cli (argc=0x2, argv=0x145c560)
    at /home/user/Desktop/php-5.6.27/sapi/cli/php_cli.c:1181
#12 0x0000000000b5a098 in main (argc=0x2, argv=0x145c560)
    at /home/user/Desktop/php-5.6.27/sapi/cli/php_cli.c:1382
#13 0x00007ffff369b830 in __libc_start_main (main=0xb5987b <main>, argc=0x2, 
    argv=0x7fffffffe1a8, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7fffffffe198)
    at ../csu/libc-start.c:291
#14 0x0000000000443ab9 in _start ()


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 [2016-11-04 05:57 UTC]
-Status: Open +Status: Closed -Assigned To: +Assigned To: stas
 [2016-11-04 05:57 UTC]
The fix for this bug has been committed.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at

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 [2017-02-13 01:06 UTC]
-Type: Security +Type: Bug
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