[Python-Dev] Newly Built Python3 Binary Throws Segfault
Cyd Haselton
chaselton at gmail.com
Fri Jan 30 21:50:39 CET 2015
Unfortunately it is still reporting the same function :-/.
On Fri, Jan 30, 2015 at 1:44 PM, Ryan Gonzalez <rymg19 at gmail.com> wrote:
> Yes...
>
> Can you check if it's crashing in a different function now?
>
> On Fri, Jan 30, 2015 at 1:39 PM, Cyd Haselton <chaselton at gmail.com> wrote:
>>
>> Yes I did. I did have to enter all the information in manually...I'm
>> not familiar with automated patch application tools and even if I
>> were, I'm pretty sure I wouldn't have them on my device.
>>
>> Just so that I'm absolutely sure I got everything correct...you wanted
>> all of the lines in the patch commented out, correct? Basically
>> everything referencing oldloc?
>>
>> On Fri, Jan 30, 2015 at 1:00 PM, Ryan Gonzalez <rymg19 at gmail.com> wrote:
>> > Are you sure the patch was applied correctly? I was SO sure it would
>> > work!
>> >
>> > FYI, you tried the patch I attached to the email message, right?
>> >
>> > On Fri, Jan 30, 2015 at 12:58 PM, Cyd Haselton <chaselton at gmail.com>
>> > wrote:
>> >>
>> >> Update: I did try the patch after getting it installed correctly, but
>> >> I'm still getting a segfault on the newly built binary.
>> >> Will post info this afternoon.
>> >>
>> >> On Fri, Jan 30, 2015 at 12:10 PM, Ryan Gonzalez <rymg19 at gmail.com>
>> >> wrote:
>> >> > No, it returns NULL if malloc gives it a raw pointer. It
>> >> > unconditionally
>> >> > checks the length of the (possibly null) string argument first.
>> >> >
>> >> > Please try the patch I attached in the last email. It *might* fix the
>> >> > issue.
>> >> > Android has crappy locale handling.
>> >> >
>> >> > On Fri, Jan 30, 2015 at 12:09 PM, Cyd Haselton <chaselton at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Unless i'm reading something incorrectly, _PyMem_RawStrdup is
>> >> >> currently returning NULL when given a null pointer.
>> >> >>
>> >> >> From obmalloc.c
>> >> >>
>> >> >> _PyMem_RawStrdup(const char *str)
>> >> >> {
>> >> >> size_t size;
>> >> >> char *copy;
>> >> >> size = strlen(str) + 1;
>> >> >> copy = PyMem_RawMalloc(size);
>> >> >> if (copy == NULL)
>> >> >> return NULL;
>> >> >> memcpy(copy, str, size);
>> >> >> return copy;
>> >> >> }
>> >> >>
>> >> >> On Fri, Jan 30, 2015 at 11:56 AM, Ryan Gonzalez <rymg19 at gmail.com>
>> >> >> wrote:
>> >> >> > I seriously doubt the issue is in that file; _PyMem_RawStrdup
>> >> >> > crashes
>> >> >> > when
>> >> >> > calling strlen. It's that whatever is calling it is likely asking
>> >> >> > it
>> >> >> > to
>> >> >> > duplicate a null pointer. Basically, it's probably the caller's
>> >> >> > fault.
>> >> >> >
>> >> >> > You could always try modifying _PyMem_RawStrdup to return NULL
>> >> >> > when
>> >> >> > given a
>> >> >> > null pointer and see where it then segfaults.
>> >> >> >
>> >> >> > On Fri, Jan 30, 2015 at 11:53 AM, Cyd Haselton
>> >> >> > <chaselton at gmail.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> Alternatively, is there a hassle-free way to find out what
>> >> >> >> changed
>> >> >> >> in
>> >> >> >> obmalloc.c between 2.7.x and 3.4.x?
>> >> >> >>
>> >> >> >>
>> >> >> >> On Fri, Jan 30, 2015 at 9:29 AM, Cyd Haselton
>> >> >> >> <chaselton at gmail.com>
>> >> >> >> wrote:
>> >> >> >> > There's a related strdup patch for readline.c, mentioned
>> >> >> >> > here:http://bugs.python.org/issue21390 and here
>> >> >> >> > https://github.com/rave-engine/python3-android/issues/2.
>> >> >> >> > There's a patch, but I'm not sure how to modify it for
>> >> >> >> > obmalloc.c,
>> >> >> >> > as
>> >> >> >> > (I think) the functions all belong to Python...they're all
>> >> >> >> > prefixed
>> >> >> >> > with _PyXx
>> >> >> >> >
>> >> >> >> > On Fri, Jan 30, 2015 at 9:05 AM, Cyd Haselton
>> >> >> >> > <chaselton at gmail.com>
>> >> >> >> > wrote:
>> >> >> >> >> Absolutely. Good thing I have addr2line on device
>> >> >> >> >>
>> >> >> >> >> /bld/python/Python-3.4.2 $ addr2line -C -f -e
>> >> >> >> >> /lib/libpython3.4m.so.1.0
>> >> >> >> >> 0008bbc8
>> >> >> >> >> _PyMem_RawStrdup
>> >> >> >> >> /bld/python/Python-3.4.2/Objects/obmalloc.c:323
>> >> >> >> >> /bld/python/Python-3.4.2 $
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >> On Thu, Jan 29, 2015 at 8:26 PM, Ryan <rymg19 at gmail.com>
>> >> >> >> >> wrote:
>> >> >> >> >>> Could you try the steps at
>> >> >> >> >>> http://stackoverflow.com/a/11369475/2097780? They
>> >> >> >> >>> allow you to get a better idea of where libc is crashing.
>> >> >> >> >>>
>> >> >> >> >>> Cyd Haselton <chaselton at gmail.com> wrote:
>> >> >> >> >>>>
>> >> >> >> >>>> Managed to get this out of logcat:
>> >> >> >> >>>> F(11914) Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1),
>> >> >> >> >>>> thread
>> >> >> >> >>>> 11914 (python) (libc)
>> >> >> >> >>>>
>> >> >> >> >>>> [ 01-29 19:30:55.855 23373:23373 F/libc ]
>> >> >> >> >>>> Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1), thread
>> >> >> >> >>>> 23373
>> >> >> >> >>>> (python)
>> >> >> >> >>>>
>> >> >> >> >>>> Less detail than strace but it seems to be that python is
>> >> >> >> >>>> segfaulting
>> >> >> >> >>>> libc...
>> >> >> >> >>>>
>> >> >> >> >>>> On Wed, Jan 28, 2015 at 11:23 AM, Ryan Gonzalez
>> >> >> >> >>>> <rymg19 at gmail.com>
>> >> >> >> >>>> wrote:
>> >> >> >> >>>>>
>> >> >> >> >>>>> On Wed, Jan 28, 2015 at 10:43 AM, Guido van Rossum
>> >> >> >> >>>>> <guido at python.org>
>> >> >> >> >>>>> wrote:
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> What I see in the strace:
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> ... load libpython3.4m.so.1.0
>> >> >> >> >>>>>> ... load libm
>> >> >> >> >>>>>> ... open /dev/__properties__ and do something to it
>> >> >> >> >>>>>> (what?)
>> >> >> >> >>>>>> ... get current time
>> >> >> >> >>>>>> ... allocate memory
>> >> >> >> >>>>>> ... getuid
>> >> >> >> >>>>>> ... segfault
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> That's not a lot to go on, but it doesn't look as if it
>> >> >> >> >>>>>> has
>> >> >> >> >>>>>> started to
>> >> >> >> >>>>>> load modules yet.
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> Does /dev/__properties__ ring a bell? Not to me.
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>> https://android.googlesource.com/platform/system/core/+/tools_r22/init/property_service.c
>> >> >> >> >>>>> is the code that works with that file.
>> >> >> >> >>>>>
>> >> >> >> >>>>> This explains it a bit (slides 24-29). Looks like
>> >> >> >> >>>>> something
>> >> >> >> >>>>> to
>> >> >> >> >>>>> do
>> >> >> >> >>>>> with
>> >> >> >> >>>>> interprocess communication. Likely has nothing to do with
>> >> >> >> >>>>> Python
>> >> >> >> >>>>> itself.
>> >> >> >> >>>>>
>> >> >> >> >>>>> Maybe this would be useful?
>> >> >> >> >>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> That stack trace would be really helpful.
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> On Wed, Jan 28, 2015 at 8:34 AM, Cyd Haselton
>> >> >> >> >>>>>> <chaselton at gmail.com>
>> >> >> >> >>>>>> wrote:
>> >> >> >> >>>>>>>
>> >> >> >> >>>>>>>
>> >> >> >> >>>>>>> Apologies...I'm not sure what a stack track is, but I do
>> >> >> >> >>>>>>> have
>> >> >> >> >>>>>>> the
>> >> >> >> >>>>>>> strace. Nearest I can tell, it happens due to an open
>> >> >> >> >>>>>>> call,
>> >> >> >> >>>>>>> though I
>> >> >> >> >>>>>>> am probably wrong.
>> >> >> >> >>>>>>> Attaching the strace output to this email. I'm going to
>> >> >> >> >>>>>>> head
>> >> >> >> >>>>>>> back to
>> >> >> >> >>>>>>> the documentation and to back out of some
>> >> >> >> >>>>>>> Android-related
>> >> >> >> >>>>>>> changes
>> >> >> >> >>>>>>> in
>> >> >> >> >>>>>>> _localemodule.c
>> >> >> >> >>>>>>>
>> >> >> >> >>>>>>> On Wed, Jan 28, 2015 at 9:43 AM, Guido van Rossum
>> >> >> >> >>>>>>> <guido at python.org>
>> >> >> >> >>>>>>> wrote:
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>> There could be a million differences relevant (unicode,
>> >> >> >> >>>>>>>> ints,
>> >> >> >> >>>>>>>> ...).
>> >> >> >> >>>>>>>> Perhaps
>> >> >> >> >>>>>>>> the importlib bootstrap is failing. Perhaps the dynamic
>> >> >> >> >>>>>>>> loading
>> >> >> >> >>>>>>>> code
>> >> >> >> >>>>>>>> changed. Did you get a stack track? (IIRC strace shows
>> >> >> >> >>>>>>>> a
>> >> >> >> >>>>>>>> syscall
>> >> >> >> >>>>>>>> trace
>> >> >> >> >>>>>>>> --
>> >> >> >> >>>>>>>> also useful, but doesn't tell you precisely how
>> >> >> >> >>>>>>>> it segfaulted.)
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>> On Wed, Jan 28, 2015 at 6:43 AM, Cyd Haselton
>> >> >> >> >>>>>>>> <chaselton at gmail.com>
>> >> >> >> >>>>>>>> wrote:
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>> All,
>> >> >> >> >>>>>>>>> I recently ditched my attempts to port Python 2.7.8 to
>> >> >> >> >>>>>>>>> Android
>> >> >> >> >>>>>>>>> in
>> >> >> >> >>>>>>>>> favor of Python 3.4.2. Unfortunately, after using the
>> >> >> >> >>>>>>>>> same
>> >> >> >> >>>>>>>>> configure
>> >> >> >> >>>>>>>>> options in the same environment, and modifying the
>> >> >> >> >>>>>>>>> setup.py
>> >> >> >> >>>>>>>>> as
>> >> >> >> >>>>>>>>> needed,
>> >> >> >> >>>>>>>>> the newly built binary throws a segfault when the
>> >> >> >> >>>>>>>>> generate-posix-vars
>> >> >> >> >>>>>>>>> portion of the build is reached...and when it is run
>> >> >> >> >>>>>>>>> as
>> >> >> >> >>>>>>>>> well
>> >> >> >> >>>>>>>>> (i.e.
>> >> >> >> >>>>>>>>> ./python --help, ./python -E -S -m sysconfig, or
>> >> >> >> >>>>>>>>> similar)
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>> I took a strace of ./python, however I'm a bit lost
>> >> >> >> >>>>>>>>> when
>> >> >> >> >>>>>>>>> reviewing
>> >> >> >> >>>>>>>>> it.
>> >> >> >> >>>>>>>>> Any ideas as to what may be going on...i.e. why Python
>> >> >> >> >>>>>>>>> 2.7
>> >> >> >> >>>>>>>>> works but
>> >> >> >> >>>>>>>>> 3.x throws a segfault?
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>> Thanks in advance,
>> >> >> >> >>>>>>>>> Cyd
>> >> >> >> >>>>>>>>> ________________________________
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>> Python-Dev mailing list
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>> Python-Dev at python.org
>> >> >> >> >>>>>>>>> https://mail.python.org/mailman/listinfo/python-dev
>> >> >> >> >>>>>>>>> Unsubscribe:
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>>
>> >> >> >> >>>>>>>>> https://mail.python.org/mailman/options/python-dev/guido%40python.org
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>>
>> >> >> >> >>>>>>>> --
>> >> >> >> >>>>>>>> --Guido van Rossum (python.org/~guido)
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> --
>> >> >> >> >>>>>> --Guido van Rossum (python.org/~guido)
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> ________________________________
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> Python-Dev mailing list
>> >> >> >> >>>>>> Python-Dev at python.org
>> >> >> >> >>>>>> https://mail.python.org/mailman/listinfo/python-dev
>> >> >> >> >>>>>> Unsubscribe:
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>>
>> >> >> >> >>>>>> https://mail.python.org/mailman/options/python-dev/rymg19%40gmail.com
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>>
>> >> >> >> >>>>> --
>> >> >> >> >>>>> Ryan
>> >> >> >> >>>>> If anybody ever asks me why I prefer C++ to C, my answer
>> >> >> >> >>>>> will
>> >> >> >> >>>>> be
>> >> >> >> >>>>> simple:
>> >> >> >> >>>>> "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't
>> >> >> >> >>>>> think
>> >> >> >> >>>>> that was
>> >> >> >> >>>>> nul-terminated."
>> >> >> >> >>>>> Personal reality distortion fields are immune to
>> >> >> >> >>>>> contradictory
>> >> >> >> >>>>> evidence.
>> >> >> >> >>>>> -
>> >> >> >> >>>>> srean
>> >> >> >> >>>>> Check out my website: http://kirbyfan64.github.io/
>> >> >> >> >>>
>> >> >> >> >>>
>> >> >> >> >>> --
>> >> >> >> >>> Sent from my Android phone with K-9 Mail. Please excuse my
>> >> >> >> >>> brevity.
>> >> >> >> >>> Check out my website: http://kirbyfan64.github.io/
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > --
>> >> >> > Ryan
>> >> >> > If anybody ever asks me why I prefer C++ to C, my answer will be
>> >> >> > simple:
>> >> >> > "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think
>> >> >> > that
>> >> >> > was
>> >> >> > nul-terminated."
>> >> >> > Personal reality distortion fields are immune to contradictory
>> >> >> > evidence.
>> >> >> > -
>> >> >> > srean
>> >> >> > Check out my website: http://kirbyfan64.github.io/
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > Ryan
>> >> > If anybody ever asks me why I prefer C++ to C, my answer will be
>> >> > simple:
>> >> > "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that
>> >> > was
>> >> > nul-terminated."
>> >> > Personal reality distortion fields are immune to contradictory
>> >> > evidence.
>> >> > -
>> >> > srean
>> >> > Check out my website: http://kirbyfan64.github.io/
>> >
>> >
>> >
>> >
>> > --
>> > Ryan
>> > If anybody ever asks me why I prefer C++ to C, my answer will be simple:
>> > "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
>> > nul-terminated."
>> > Personal reality distortion fields are immune to contradictory evidence.
>> > -
>> > srean
>> > Check out my website: http://kirbyfan64.github.io/
>
>
>
>
> --
> Ryan
> If anybody ever asks me why I prefer C++ to C, my answer will be simple:
> "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
> nul-terminated."
> Personal reality distortion fields are immune to contradictory evidence. -
> srean
> Check out my website: http://kirbyfan64.github.io/
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