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Date: Sat, 31 Oct 2020 10:47:36 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH v2] MT fork

On Sat, Oct 31, 2020 at 09:22:04AM +0200, Timo Teras wrote:
> Hi
> 
> On Fri, 30 Oct 2020 15:31:54 -0600
> Ariadne Conill <ariadne@...eferenced.org> wrote:
> 
> > On Friday, October 30, 2020 12:57:17 PM MDT Rich Felker wrote:
> > > There was a regression in musl too, I think. With
> > > 27b2fc9d6db956359727a66c262f1e69995660aa you should be able to
> > > re-enable parallel mark. If you get a chance to test, let us know if
> > > it works for you.  
> > 
> > I have pushed current musl git plus the MT fork patch to Alpine edge
> > as Alpine musl 1.2.2_pre0, and reenabling parallel mark has worked
> > fine.
> > 
> > It would be nice to have a musl 1.2.2 release that I can use for the
> > source tarball instead of a git snapshot, but this will do for now.
> 
> And now firefox is utterly broken. Though seems to be not related to MT
> fork patch.
> 
> Bisected it down to commit b8b729bd22c28c9116c2fce65dce207a35299c26
> "fix missing O_LARGEFILE values on x86_64, x32, and mips64"
> 
> I think this breaks the seccomp because now e.g. fopen() calls has this
> bit set for the syscall and seccomp does not like it.
> 
> Wondering whether to fix firefox seccomp ignore this bit, or if this
> commit needs reconsideration?

Firefox needs to be fixed. A seccomp filter error is *always* the
filter being wrong.

Further, there should be a real audit of these filters (I'm willing to
do it myself if someone can dig up the code I need to look at) to
prevent this kind of thing preemptively. Any reasonable review would
have shown this code was wrong if blocking the bit was specific to
x86_64 and a few other archs, and if it's not specific, all the other
archs were already broken. I'm pretty sure we'll find a lot of other
issues that need to be fixed, some of them probably breaking
less-popular archs right now.

Rich

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