Null pointer dereference

[bird8693]

Enviroment

operating system: ubuntu18.04
compile command: ./configure && make
test command: ./run_tests poc

poc:

https://drive.google.com/open?id=1LDDlXy5TT1GcVikKCdYtbCjBKtBGGhJ_

vulnerability description:

It is a problem with CTinyJS :: factor. On the TinyJS.cpp + 1663 line, a null pointer reference is triggered, as shown in the figure:

The reason for the vulnerability is that when a temporary assignment variable a is generated, it is not verified whether a is empty, and then a-> var refers to a, which causes the vulnerability.

poc construction

In the process of declaring a variable, a null pointer can be caused by adding a null character.

That is, an empty character is added after an element of the array.