Bug#840580: apache2-bin: crashes when issuing a restart while mod_cgid is enabled

[Stefan Fritsch <sf@sfritsch.de>]

On Sunday, 25 November 2018 19:07:56 CET Bernhard Übelacker wrote:
> Dear Maintainer,
> tried to find out the actual location that the backtrace points to.
> 
> Unfortunately I could not make any clue out of the line
> containing /usr/sbin/apache2(+0x29e450).
> 
> But at least, I think, the line containing mod_mpm_prefork.so(+0x4c08)
> translates to function prefork_run in server/mpm/prefork/prefork.c.
> 
> As this is a rather big function, and looks like it is never left while
> the server runs, and there are no local arrays accessed, the stack
> canary may be overwritten by some function called from there.
> But the stack canary is just checked when prefork_run exits.
> 
> Kind regards,
> Bernhard

The  "bt full" gdb command is the important one. Please show its output as 
described in README.backtrace