Re: [HELP] [bug #55475] Segmentation fault in libgroff:relocatep

[John Gardner]

>
> In fact, we could really use ongoing assistance from someone with a
> Windows environment to test builds on.


These VirtualBox images might help to bridge a few gaps…

   - https://archive.org/details/ie6.xp.virtualbox
   - https://archive.org/details/ie8.xp.virtualbox
   - https://archive.org/details/ie8.win7.virtualbox
   - https://archive.org/details/ie9.win7.virtualbox
   - https://archive.org/details/ie10.win7.virtualbox
   - https://archive.org/details/ie11.win7.virtualbox
   - https://archive.org/details/ie11.win81.virtualbox
   - https://archive.org/details/msedge.win10.virtualbox

These contain 90-day trial versions of Windows, formerly provided by
Microsoft for web developers testing their sites against legacy versions of
Internet Explorer. After a while, Microsoft stopped bothering to host older
VMs altogether:

   - https://github.com/xdissent/ievms/issues/341
   - https://gist.github.com/zmwangx/e728c56f428bc703c6f6

I uploaded a copy of each VM I was fortunate enough to find a mirror for. I
did this out of historical curiosity (and also to spite anybody at
Microsoft hoping to whitewash memories of IE6 from the world, heh). FWIW, I
cross-checked the SHA256 sums of a few images with those I happened to have
backed up to a portable hard-drive. That's more of an anecdote than a
statement about file integrity, though.

*@Branden*: I recommend mounting these images in VirtualBox without network
access or write access to shared folders. Download installer files ahead of
time and expose it as a read-only shared directory. If MinGW doesn't work, GOW
should work <https://github.com/bmatzelle/gow>. I'm sure you can work out
the rest. ;-)

Once the 90-day trial period expires, you'll be limited to time-locked
Windows sessions (unless you reinstall the VM from scratch; note that
rolling back to a VM snapshot doesn't always fool Windows).








On Wed, 6 Jan 2021 at 16:17, G. Branden Robinson <
g.branden.robinson@gmail.com> wrote:

> [redirecting from bug-groff@]
>
> I deeply hate hacking on C when I have no reproducible test case I can
> use and no access to a system that exercises the code paths I'm
> troubleshooting.  But this bug has been sitting for a long time and it
> seems no one wants to touch it.
>
> Details below.
>
> `make distcheck` passed for each of these commits on my Debian-based
> x86-64 system but that doesn't tell us much since the problem only ever
> manifested on other configurations.
>
> I could use confirmation of two things:
>
> (1) What happens when Guix reverts the workaround patch discussed in
>     <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=30785>, letting this
>     code get exercised.  I predict an assertion failure.  If I'm right,
>     then the bug has been RCAed and we can decide how to make
>     relocatep() cope with the issue.
>
> (2) Whether these changes break things for Windows users.
>
> In fact, we could really use ongoing assistance from someone with a
> Windows environment to test builds on.
>
> Regards,
> Branden
>
> At 2021-01-05T23:59:10-0500, G. Branden Robinson wrote:
> > Update of bug #55475 (project groff):
> >
> >                   Status:               Confirmed => Need Info
>
> >              Assigned to:                    None => gbranden
>
> >
> >     _______________________________________________________
> >
> > Follow-up Comment #5:
> >
> > Well, no one has stepped up to this, and I can't reproduce it, but I also
> > can't stand the thought of groff 1.23.0 going out with this bug, so with
> > considerable discomfort I took a stab at it.
> >
> > I've pushed the following 3 commits to try and get at the issue.  A tar
> > archive of the tree can be obtained from:
> >
> >
> https://git.savannah.gnu.org/cgit/groff.git/commit/?id=2fabd352f4ccdb382acffb7705a129977a2768d3
> >
> > Or I can easily prepare a distribution archive from any of these three
> points
> > if that would help.
> >
> > I need someone's help to confirm whether the issue has been resolved, or
> to
> > observe the assertion failure!
> >
> >
> > commit 2fabd352f4ccdb382acffb7705a129977a2768d3 (HEAD -> master,
> > origin/master, origin/HEAD)
> > Author: G. Branden Robinson <g.branden.robinson@gmail.com>
> > Date:   Wed Jan 6 15:48:39 2021 +1100
> >
> >     src/libs/libgroff/relocate.cpp: Shift #ifdef.
> >
> >     * src/libs/libgroff/relocate.cpp (set_current_prefix) [!_WIN32]: Move
> >       logic attempting to set `curr_prefix` by calling searchpathext()
> from
> >       here...
> >       [WIN32]: ...to here.  The PATHEXT environment variable has
> semantics
> >       only under Windows, not POSIX systems, so the placement of this
> code
> >       seemed erroneous.
> >
> > commit c2f0e424e4a2bdcd287c8be9957daf93a581673a
> > Author: G. Branden Robinson <g.branden.robinson@gmail.com>
> > Date:   Wed Jan 6 15:43:57 2021 +1100
> >
> >     src/libs/libgroff/relocate.cpp: Fix memory leak.
> >
> >     * src/libs/libgroff/relocate.cpp (set_current_prefix) [_WIN32]:
> Allocate
> >       memory from heap for `curr_prefix` only on Windows; on other
> systems,
> >       this file's searchpath() is used to populate `curr_prefix`, and
> that
> >       function (except on Windows) performs its own allocation.  Fixes
> >       memory leak noted by Ingo Schwarze.
> >
> > commit 89c98409d32d01867e6f7cb7ab61efaf7b1da67e
> > Author: G. Branden Robinson <g.branden.robinson@gmail.com>
> > Date:   Wed Jan 6 15:34:50 2021 +1100
> >
> >     [libgroff]: (relocatep) Add assertion.
> >
> >     * src/libs/libgroff/relocate.cpp (relocatep): Add assertion to
> identify
> >       logic error if `curr_prefix` is unexpectedly a null pointer.  See
> >       <https://savannah.gnu.org/bugs/?55475>.
> >
> >
> >     _______________________________________________________
> >
> > Reply to this item at:
> >
> >   <https://savannah.gnu.org/bugs/?55475>
> >
> > _______________________________________________
> >   Message sent via Savannah
> >   https://savannah.gnu.org/
> >
>