Re: Gimp git on Mac Segfault

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Hi,

I searched a little more though, and it seems on BSDs, hence on OSX,
indeed setenv with a NULL value could crash the program. The setenv in
GNU libc on the other hand perfectly handles the case explicitly.
So obviously when I see this kind of code (note I am not 100% sure
this is the code for Darwin on Mountain Lion but I can't find a
reference linking the libc numbers there and the Darwin version 10.8,
but I assume that should be a similar code):
http://www.opensource.apple.com/source/Libc/Libc-825.26/stdlib/FreeBSD/setenv.c

Before any test on the value pointer, it dereferences it (which is
undefined!), and read the content of the non-existing first character
of the NULL string (which I assume would crash!):

if (*value == '=') /* no `=' in value */
++value;

I don't know what is the policy on BSD but I thought they were very
keen on security, but this code does not look very sane to me.
So yeah anyway that's a problem too in the end. I'll deal with it.

Jehan


On Fri, Jul 19, 2013 at 7:14 AM, Partha Bagchi <partha1b@xxxxxxxxx> wrote:
> Jehan,
>
> I will test it tomorrow. I will get back to you with the results.
>
> Thanks for your prompt response!
>
> Partha
>
>
>
> On Thu, Jul 18, 2013 at 11:42 AM, Jehan Pagès <jehan.marmottard@xxxxxxxxx>
> wrote:
>>
>> Hi again,
>>
>> I have some working code in my working branch now where I applied the
>> concepts I wrote about (basically initializing the language store only
>> once and at the very start of the program, before any threading would
>> occur hopefully).
>> Don't know if that will be the finale code, but should be at least
>> good enough to test on OSX (I don't have access to a OSX machine to
>> reproduce the bug myself and see if this indeed fixes the issue). As
>> soon as the report is up, I'll upload the patch there so that someone
>> with OSX can test it and tell me if that fixes it. :-)
>> Thanks.
>>
>> Jehan
>>
>>
>> On Thu, Jul 18, 2013 at 9:47 PM, Jehan Pagès <jehan.marmottard@xxxxxxxxx>
>> wrote:
>> > Hey all,
>> >
>> > it seems I am the culprit for this bug. I don't have this crash on Linux
>> > though.
>> >
>> > It looks like the implementation of setenv/getenv is different on OSX.
>> > According to glib doc, the problem may be that on some
>> > implementations, successive calls may use the same buffer. I guess
>> > that's the case on OSX. And also these calls are not thread-safe. Also
>> > the fact that there is no LANGUAGE env variable should normally not be
>> > a real problem. I don't have this variable set on my system either
>> > and, as I said, no crash here. I guess this brought the real issue of
>> > the OSX getenv/setenv implementation into light though.
>> >
>> > In any case, I think that the real solution is to have the list of all
>> > localized languages generated at startup, before any thread or
>> > anything happens (I just saw that's also what glib doc says: we should
>> > only use these calls on startup before any thread happens). Then we
>> > just use this pre-generated list each time it is needed. I was already
>> > thinking that the current design was bad anyway, because we are
>> > basically parsing a huge file of language codes and names each time we
>> > open the preference dialog! Such a waste of resources and time.
>> > I did not modify it at the time because I did not feel like using more
>> > time towards this, but I guess that should be the occasion to do it.
>> >
>> > In any case, please fill a bug report and I'll have a look! :-)
>> >
>> > Jehan
>> >
>> >
>> > On Thu, Jul 18, 2013 at 6:31 AM, Partha Bagchi <partha1b@xxxxxxxxx>
>> > wrote:
>> >> Hey V,
>> >>
>> >> Thanks for checking on this. I am glad (in a way) that my system is not
>> >> the
>> >> only one having this issue! :)
>> >>
>> >> I will try to revert the above changes and see if the problem
>> >> disappears.
>> >>
>> >> Partha
>> >>
>> >>
>> >>
>> >> On Wed, Jul 17, 2013 at 7:51 AM, su_v <suv-sf@xxxxxxxxxxxxxxxxxxxxx>
>> >> wrote:
>> >>
>> >>> On 2013-07-17 01:19 +0100, Partha Bagchi wrote:
>> >>> > My recent (last built a few moment ago) git builds (2.9) have been
>> >>> > instantly segfaulting on MBR running Mountain Lion.
>> >>> >
>> >>> > gdb backtrace (or commandline execution) shows:
>> >>> > ./gimp-2.9 (pid:42315): [E]xit, [H]alt, show [S]tack trace or
>> >>> > [P]roceed:
>> >>> S
>> >>> > #0  0x00007fff8b257698 in __wait4 ()
>> >>> > #1  0x00000001018de353 in g_on_error_stack_trace ()
>> >>> > #2  0x00000001018de7f2 in g_on_error_query ()
>> >>> > #3  0x000000010000fa54 in gimp_eek ()
>> >>> > #4  0x000000010000fac8 in gimp_fatal_error ()
>> >>> > #5  0x0000000100010326 in gimp_sigfatal_handler ()
>> >>> > #6  <signal handler called>
>> >>> > #7  0x00007fff8c40887e in setenv ()
>> >>> > #8  0x00000001018f76cf in g_setenv ()
>> >>> > #9  0x0000000100168c11 in gimp_language_store_self_l10n ()
>> >>> > #10 0x0000000101915c99 in emit_start_element ()
>> >>> > #11 0x00000001019170b0 in g_markup_parse_context_parse ()
>> >>> > #12 0x000000010035a7ba in gimp_xml_parser_parse_io_channel ()
>> >>> > #13 0x000000010035a9ab in gimp_xml_parser_parse_file ()
>> >>> > #14 0x0000000100168f71 in gimp_language_store_parse_iso_codes ()
>> >>> > #15 0x000000010188619b in g_object_new_internal ()
>> >>> > #16 0x0000000101886cdd in g_object_newv ()
>> >>> > #17 0x0000000101886edc in g_object_new ()
>> >>> > #18 0x0000000100168025 in gimp_language_entry_new ()
>> >>> > #19 0x000000010017cc00 in gimp_prop_language_entry_new ()
>> >>> > #20 0x00000001000a3df2 in gimp_text_options_gui ()
>> >>> > #21 0x000000010005e9e6 in gimp_tools_restore ()
>> >>> > #22 0x000000010001428b in gui_restore_callback ()
>> >>> > #23 0x000000010187dd0d in g_closure_invoke ()
>> >>> > #24 0x000000010189483b in signal_emit_unlocked_R ()
>> >>> > #25 0x0000000101897111 in g_signal_emit_valist ()
>> >>> > #26 0x0000000101897964 in g_signal_emit ()
>> >>> > #27 0x000000010000f2fe in app_run ()
>> >>> > #28 0x0000000100011994 in main ()
>> >>> >
>> >>> > and gimp-2.9 --verbose
>> >>> > ...
>> >>> > Parsing '/Users/partha/Library/Application
>> >>> > Support/GIMP/2.9/tool-options/gimp-text-tool'
>> >>> > ./gimp-2.9: fatal error: Segmentation fault: 11
>> >>> > ./gimp-2.9 (pid:42330): [E]xit, [H]alt, show [S]tack trace or
>> >>> > [P]roceed:
>> >>> >
>> >>> > Is anyone else on the Mac having this issue? Should I file a
>> >>> > bug-report?
>> >>>
>> >>> Reproduced (same stack trace) on MBR (13-inch, Late 2011) running OS X
>> >>> 10.7.5; dependencies for GIMP installed via MacPorts (custom portfiles
>> >>> for babl, gegl and GIMP git master).
>> >>>
>> >>> Workaround (at least for this segfault at launch time) is to run GIMP
>> >>> like this:
>> >>>
>> >>> $ echo $LANG
>> >>> en_US.UTF-8
>> >>> $ LANGUAGE="$LANG" gimp --verbose
>> >>>
>> >>>
>> >>> Possibly related to the changes in
>> >>> <
>> >>>
>> >>> https://git.gnome.org/browse/gimp/commit/?id=f6dcde1ee66fda4dfdc063022c4d2e901adb9a71
>> >>> >
>> >>> <
>> >>>
>> >>> https://git.gnome.org/browse/gimp/commit/?id=4eecd9b4ac71615f10819378938dcdce7e531167
>> >>> >
>> >>>
>> >>>
>> >>> hth, V
>> >>> _______________________________________________
>> >>> gimp-developer-list mailing list
>> >>> List address:    gimp-developer-list@xxxxxxxxx
>> >>> List membership:
>> >>> https://mail.gnome.org/mailman/listinfo/gimp-developer-list
>> >>>
>> >> _______________________________________________
>> >> gimp-developer-list mailing list
>> >> List address:    gimp-developer-list@xxxxxxxxx
>> >> List membership:
>> >> https://mail.gnome.org/mailman/listinfo/gimp-developer-list
>
>
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