[ros-dev] R: [ros-diffs] 01/01: [WINLOGON] Clean up part 2 - Replace the UNICODE_STRING usMessage by a PWSTR pszMessage. - Use the "%02d:%02d:%02d" time format and get rid of the safe string printf because the string will NEVER be longer than 8 charac...

[Riccardo Paolo Bestetti]

Some people use the very same argument to write OS’s in Rust. It’s not like it doesn’t
make sense, it’s just not necessary.
If C++ and Rust can compile to safe code, so can C. You just gotta define and abide by
sensible safety practices.

</stating_the_obvious>

BR,
Riccardo P. Bestetti

Da: Ros-dev [mailto:[e-mail]] Per conto di Huw Campbell
Inviato: giovedì 5 aprile 2018 13:35
A: ReactOS Development List &lt;ros-dev(a)reactos.org&gt;
Oggetto: Re: [ros-dev] [ros-diffs] 01/01: [WINLOGON] Clean up part 2 - Replace the
UNICODE_STRING usMessage by a PWSTR pszMessage. - Use the "%02d:%02d:%02d" time
format and get rid of the safe string printf because the string will NEVER be longer than
8 charac...

Hey,

I'm going to chime in here.

If you want to fix this problem: Don't use C! Use C++, C#, Java etc. instead!

Honestly, this is inane right? ReactOS currently uses C predominantly, but we can't
use that as an excuse for shitty code which breaks, crashes, or has buffer overflows.
Security issues are not ok.

Cheers,
Huw


On Tue, Apr 3, 2018 at 5:53 AM, Thomas Faber
<[e-mail]<mailto:[e-mail]>> wrote:
Finding bugs is definitely a valid concern. But there is, of course,
a version that addresses both problems:
NT_VERIFY(NT_SUCCESS(RtlStringCbPrintfW(...)));

This will assert in case the buffer is too small, while still never
causing an overflow.

We could provide wrappers to require less typing or raise an exception
even on release builds, if that's more desirable.

Best,
Thomas



On 2018-04-02 20:28, Magnus Johnsson wrote:
>   Eric, the thing is, buffer overflows don't just
> crash the program unless
>  you have some really nifty guard pages, but overwrite other things in
>  memory. This means an attacker can, in certain situations, use it to create
>  something that not just crashes, but with a nifty input create an exploit.
>  Having a 'Oh it will just crash' attitude is 'not the best'.
>
>  2018-04-02 19:41 GMT+02:00 Eric Kohl
> <[e-mail]<mailto:[e-mail]>>:
>
> > Hello Thomas,
> >
> > you're right, using the run-time size checks are a good way to keep
> > application from crashing because of buffer overflows. They'll just keep
> > on using corrupt data instead! If you want to fix this problem: Don't
> > use C! Use C++, C#, Java etc. instead!
> >
> > I prefer to see an application crash because of a buffer overflow rather
> > than seeing it store truncated phone numbers in a database.
> >
> > PS: If the timeout is longer than a day, winlogon uses the "%d days"
> > format. In the end, a buffer of 10 characters is still large enough.
> >
> > PPS: I'll keep using the old functions until you remove them from the
> > runtime code.
> >
> >
> > Regards
> > Eric
> >
> > Am 02.04.2018 um 14:12 schrieb Thomas Faber:
> >> Hey Eric,
> >>
> >> On 2018-04-02 12:58, Eric Kohl wrote:
> >>> -    RtlStringCbPrintfW(strbuf, sizeof(strbuf), L"%d:%d:%d",
> hours,
> >>> minutes, seconds);
> >>> +    swprintf(szBuffer, L"%02d:%02d:%02d", iHours, iMinutes,
> iSeconds);
> >>
> >> Unfortunately I must disagree with this change.
> >>
> >> Buffer overflows are a big enough threat that code review and
> >> static analysis are not generally considered sufficient to protect
> >> against them.
> >> So it's best practice for new code to always verify sizes at run-time,
> >> and never to use s(w)print.
> >>
> >> Best regards,
> >> Thomas
> >>
> >> PS: from what I see, iHours can be as large as 1193046, which won't
> >>      fit in 2 digits
>  

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