Re: [PATCH v2] plugins/stoptrigger: TCG plugin to stop execution under conditions

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 7/15/24 01:09, Simon Hamelin wrote:
> Hello Pierrick,
> 
>> Could you share a bit more information on the final goal, if possible?
>> Is that used for fuzzing binaries, security analysis, or other things?
> 
> I'm currently using this plugin for security analysis purposes.
> Basically my goal is to simulate fault injection using QEMU. To do so
> I'm using this plugin along with another plugin that skips an
> instruction at a given address. With this plugin I'm able to see how the
> program reacts to the fault and stop it with a custom return code.
> Basically there are 4 cases:
>      - The fault does not disrupt the program and it reaches the expected
> address.
>      - The fault disrupt the program and it reaches an unexpected address
> known as the "target" address.
>      - The fault disrupt the program in such a way that it executes a lot
> of instructions without reaching the expected address, this situation is
> known as a "timeout".
>      - The fault crashes the guest, causing it to reach an error handler
> address.
> 

Thanks for sharing this, it's an interesting use case.

How did you implement instruction skipping?
Is that based on current API, or do you have a QEMU fork?

> In short, here's a command line that illustrates how I use the plugin:
> 
> $ qemu-system-aarch64 $(QEMU_ARGS) -plugin
> ./contrib/plugins/libstoptrigger.so,icount=timeout_count,addr=addr=expected_addr:0,error_handler_addr:1,target_addr:2
> -d plugin
> 
> --
> Simon Hamelin