Edit report at https://bugs.php.net/bug.php?id=60798&edit=1
ID: 60798
Updated by: rasmus@php.net
Reported by: ktk at enterprise dot bidmc dot harvard dot edu
Summary: Regression: uninitialized memory in
openssl_encrypt() with zero-length $data
-Status: Open
+Status: Assigned
Type: Bug
Package: OpenSSL related
Operating System: Slackware x86_64
PHP Version: 5.3.9
-Assigned To:
+Assigned To: scottmac
Block user comment: N
Private report: N
Previous Comments:
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[2012-01-19 03:08:18] ktk at enterprise dot bidmc dot harvard dot edu
Description:
------------
A regression was introduced in php 5.3.9 to the file ext/openssl/openssl.c which causes
openssl_encrypt("", "aes-128-cbc", "password") to use uninitialized
memory when calling the underlying AES_cbc_encrypt() whenever the length of the $data argument is
zero. This results in either a corrupted return value, or a segmentation fault, depending upon what
exists in php's memory heap.
I bisected the code difference between php 5.3.8 and 5.3.9 and have attached the errant patch to
this bug report.
The problem patch introduces the following code, which for reasons unknown fails to call the update
function whenever the length of the data argument is zero:
- EVP_EncryptUpdate(&cipher_ctx, outbuf, &i, ...);
+ if (data_len > 0) {
+ EVP_EncryptUpdate(&cipher_ctx, outbuf, &i, ...);
+ }
Reverting the attached patch fixes the problem for me.
I'm seeing this problem on both x86_64 (64 bit) and i686 (32 bit) processor architectures. OS
is Slackware in both cases, with php linked against openssl version 1.0.0g (ditto for openssl 1.0.0e
and 1.0.0f), glibc 2.14.1 and compiled with gcc 4.5.3.
The corruption/segfault occurs whether or not an initialization vector is passed to the function;
the only requirement it seems is the zero-length data (ergo, the omission of the call to
EVP_EncryptUpdate()).
Test script:
---------------
<?php
var_dump(openssl_encrypt("", "aes-128-cbc", "password",
false, str_repeat(chr(0), 16)));
$vec = str_repeat(chr(0), 16);
var_dump(openssl_encrypt("", "aes-128-cbc", "password",
false, $vec));
var_dump(openssl_encrypt("", "aes-128-cbc", "password"));
unset($vec);
$memory = "Let's use some memory!";
$vec = str_repeat(chr(0), 16);
var_dump(openssl_encrypt("", "aes-128-cbc", "password",
false, $vec));
?>
Expected result:
----------------
string(24) "xrQjTh0HCclFET5PKpYH9w=="
string(24) "xrQjTh0HCclFET5PKpYH9w=="
Warning: openssl_encrypt(): Using an empty Initialization Vector (iv) is potentially insecure and
not recommended in test.php on line 7
string(24) "xrQjTh0HCclFET5PKpYH9w=="
string(24) "xrQjTh0HCclFET5PKpYH9w=="
Actual result:
--------------
GNU gdb (GDB) 7.2
Reading symbols from /usr/bin/php...done.
(gdb) set args test.php
(gdb) run
Starting program: /usr/bin/php test.php
[Thread debugging using libthread_db enabled]
string(24) "AMa0I04dBwnJRRE+TyqWB/c="
string(24) "xrQjTh0HCclFET5PKpYH9w=="
Warning: openssl_encrypt(): Using an empty Initialization Vector (iv) is potentially insecure and
not recommended in test.php on line 7
string(24) "xrQjTh0HCclFET5PKpYH9w=="
Program received signal SIGSEGV, Segmentation fault.
0xb767cb7c in AES_cbc_encrypt () from /lib/libcrypto.so.1
(gdb)
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Edit this bug report at https://bugs.php.net/bug.php?id=60798&edit=1