port-amd64/54905: X server terminated with error segmentation fault at address 0x7c382b6dd000

[guest01%cyberia.pl@localhost]

>Number:         54905
>Category:       port-amd64
>Synopsis:       X server terminated with error segmentation fault at address 0x7c382b6dd000
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jan 28 21:40:00 +0000 2020
>Originator:     guest01
>Release:        8.1
>Organization:
-
>Environment:
NetBSD localhost 8.1_STABLE NetBSD 8.1_STABLE (GENERIC) #0: Tue Jan  7 12:01:32 UTC 2020  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
When you work with an application X server aborts to text mode. THE PROBLEM DOES NOT APPEAR IN NETBSD 8.0 ON THE SAME COMPUTER.

The tail of Xorg.0.log file:

[  6931.866] (EE) Segmentation fault at address 0x7c382b6dd000
[  6931.866] (EE) 
Fatal server error:
[  6931.866] (EE) Caught signal 11 (Segmentation fault). Server aborting
[  6931.866] (EE) 
[  6931.867] (EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.X.Org
 for help. 
[  6931.867] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[  6931.867] (EE) 
[  6931.868] (II) AIGLX: Suspending AIGLX clients for VT switch
[  6932.371] (EE) Server terminated with error (1). Closing log file.

>How-To-Repeat:
1. Install NetBSD 8.1 on PC computer
2. Run X Windows with startx
2. Install firefox68 from ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/x86_64/8.0_2019Q4/All
3. Start, browse any pages and close firefox a few times

>Fix: