Re: [stos, again] Re: CVS commit: src/sys/arch/amd64

[Andrew Doran <ad%netbsd.org@localhost>]

On Wed, Jun 03, 2020 at 02:03:22AM +0200, Kamil Rytarowski wrote:

> On 03.06.2020 01:49, Andrew Doran wrote:
> > On the assembly thing recall that recently you expressed a desire to remove
> > all of the amd64 assembly string functions from libc because of sanitizers -
> > I invested my time to do up a little demo to try and show you why that's not
> > a good idea:
> > 
> > 	http://mail-index.netbsd.org/port-amd64/2020/04/19/msg003226.html
> 
> Please note that interceptors for string functions are not just some
> extra burden, but also very useful approach to feedback a fuzzer through
> additional coverage.
>
> At least libFuzzer and honggfuzz wrap many kinds of string functions and
> use it for fuzzing. We should add a special mode in KCOV to feedback
> userland (syzkaller) with traces from string functions.
> 
> https://github.com/google/honggfuzz/blob/bbb476eec95ad927d6d7d3d367d2b3e38eed3569/libhfuzz/memorycmp.c#L24

No argument from me there at all.  I think that's a great idea and was
looking at the interceptors in TSAN recently to see how they work.

Andrew