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[Bug stdio/20200] dprintf unconditionally calls malloc
- From: "fweimer at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Fri, 03 Jun 2016 17:39:51 +0000
- Subject: [Bug stdio/20200] dprintf unconditionally calls malloc
- Auto-submitted: auto-generated
- References: <bug-20200-131 at http dot sourceware dot org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=20200
--- Comment #4 from Florian Weimer <fweimer at redhat dot com> ---
(In reply to Carlos O'Donell from comment #3)
> (In reply to Florian Weimer from comment #2)
> > (In reply to Carlos O'Donell from comment #1)
> > > Note that dprintf need not be AS-safe, POSIX doesn't mandate it, and we
> > > don't document any safety standard for it in the glibc manual, nor in the
> > > linux man pages project. The original author of the interface (Roland
> > > McGrath) has stated that he intended it to be AS-safe, but we don't know if
> > > that's even possible today.
> > >
> > > I don't quite understand why this is filed as a distinct bug from bug 16060?
> >
> > It's a regression in 2.23. It's fix probably will not address the other
> > issues in bug 16060.
>
> What's the regression?
Before, you could call dprintf from a signal handler, interrupting malloc, and
it would work if the format string was reasonable (no self-deadlock). After
the change to use malloc for the temporary buffer instead of mmap, you end up
with a self-deadlock.
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