Bug#950890: xserver-xorg-core: X segfaults when displaying a big image with xzgv

[Michel Dänzer <michel@daenzer.net>]

On 2020-02-07 9:33 p.m., Frédéric Brière wrote:
> Package: xserver-xorg-core
> Version: 2:1.20.7-2
> Severity: important
> 
> I can (reliably) get X to segfault when displaying a big image (say,
> over 10000x10000) with xzgv.  And since that viewer allows doubling the
> scale of an image with a single keystroke, this can easily be triggered
> with any image (which is how I accidentally ran into it in the first
> place).
> 
> Steps to reproduce:
> 
>   - View any image (the bigger the better) with xzgv
>   - Repeatedly press "d" until the server segfaults
> 
> The error message is identical to #912325, although I am using the
> radeon driver:
> 
>   [ 94509.215] (EE) glamor0: GL error: GL_OUT_OF_MEMORY in glBufferData
>   [ 94509.215] (EE) glamor0: GL error: GL_INVALID_OPERATION in glReadPixels(out of bounds PBO access)
>   [ 94509.215] (EE) glamor0: GL error: GL_INVALID_OPERATION in glMapBuffer(length = 0)
> 
> This was encountered with 2:1.20.7-2, and confirmed to be still present
> in -3.
> 
> Full log and backtrace with symbols are attached.

Can't see the backtrace, but the log excerpt above looks like the fixes
from https://gitlab.freedesktop.org/xorg/xserver/merge_requests/135
might help, so I added them to
https://gitlab.freedesktop.org/xorg/xserver/merge_requests/391 and they
will hopefully be in the upcoming 1.20.8 release.


-- 
Earthling Michel Dänzer               |               https://redhat.com
Libre software enthusiast             |             Mesa and X developer