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bug#47094: 27.1; emacs dies with XBM display
From: |
Alan Third |
Subject: |
bug#47094: 27.1; emacs dies with XBM display |
Date: |
Sat, 13 Mar 2021 22:07:14 +0000 |
On Sat, Mar 13, 2021 at 09:19:17AM +0200, Eli Zaretskii wrote:
> > Date: Fri, 12 Mar 2021 22:08:10 +0000
> > From: Alan Third <alan@idiocy.org>
> >
> > > > (let* ((w 256)
> > > > (h 256)
> > > > (s (make-string (* (/ w 8) h) #x55)))
> > > > (insert-image (create-image s 'xbm t :width w :height h)))
> > >
> > > I can reproduce in Emacs 27, but not on the current master branch. So
> > > I guess this has been fixed already, and I'm closing the bug.
> >
> > I can reproduce on the master branch. It looks like a stack overflow
> > in xbm_read_bitmap_data.
>
> I did indeed get an infinite recursion on the emacs-27 branch, but not
> on master.
>
> > I tried it in a debugger, but the backtrace looks truncated.
>
> Before or after SIGSEGV? If it's after, then it isn't surprising you
> get a truncated backtrace.
>
> I think if you see the infinite recursion we should understand why it
> happens in the first place, and try to prevent it.
It turns out it was a buffer overflow in xbm_scan that was clobbering
the stack. I've pushed a fix to the master branch.
--
Alan Third