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Date: Thu, 15 Mar 2018 16:00:37 -0300
From: "dgutson ." <danielgutson@...il.com>
To: musl@...ts.openwall.com
Subject: Re: Re: #define __MUSL__ in features.h

On Thu, Mar 15, 2018 at 3:53 PM, Rich Felker <dalias@...c.org> wrote:

> On Thu, Mar 15, 2018 at 03:48:32PM -0300, Martin Galvan wrote:
> > 2018-03-15 15:39 GMT-03:00 Rich Felker <dalias@...c.org>:
> > >> (e.g. the FD* issue reported by Martin Galvan).
> > >
> > > That's not a bug. It's compiler warnings being wrongly produced for a
> > > system header, probably because someone added -I/usr/include or
> > > similar (normally GCC suppresses these).
> >
> > I'm certain we didn't add -I/usr/include or something similar. Could
> > you test this yourself to confirm it's not a bug?
>
> In any case it's not a bug in musl. The code is perfectly valid C. If
> the compiler is producing a warning for it, either ignore it or ask
> the compiler to stop.
>
> > The compiler warnings aren't being wrongly produced. musl will indeed
> > perform a signed-to-unsigned conversion here.
>
> Because that's how the C language works.
>

it is a potential vulnerability:
https://cwe.mitre.org/data/definitions/195.html
https://wiki.sei.cmu.edu/confluence/display/c/INT31-C.+Ensure+that+integer+conversions+do+not+result+in+lost+or+misinterpreted+data
https://wiki.sei.cmu.edu/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap

Can you ensure it is rocksolid and the signed integer will NEVER be a
negative value?


>
> > > The musl policy regarding not having a macro like __MUSL__ is doing
> > > exactly what it's intended to do: encouraging developers and package
> > > maintainers to come to us (or investigate on their own) and fix the
> > > underlying portability problems (and sometimes musl bugs) rather than
> > > writing hacks to a specific version of musl that will be wrong a few
> > > versions later.
> >
> > So whenever we find a bug on musl we should just stop all our
> > development until you've fixed the bug?
>
> No. As noted above, if you need to support systems that might have bug
> X, you write a test (configure-time or run-time as appropriate) to
> detect bug X and handle it.
>
> Rich
>



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