[Python-Dev] Newly Built Python3 Binary Throws Segfault
Ryan Gonzalez
rymg19 at gmail.com
Fri Jan 30 23:19:02 CET 2015
Do you have the Android SDK and NDK installed? If so...
Using Google, I've created this series of steps, which may (or may not)
work:
1. Make sure you have a copy of Python on your computer and make sure that
it's built with debug symbols.
2. Run the following commands from a shell with your phone plugged in:
adb forward tcp:5039 tcp:5039
adb shell /system/bin/gdbserver tcp:5039 <path to python executable>
<path to ndk binary folder>/arm-linux-androideabi-gdb
Now, GDB should have opened, so type the following commands:
set solib-search-path <directory holder libpython.so>
file <path to local python executable>
target remote :5055
run
Now, wait for the program to crash and type:
backtrace
You should now see a complete backtrace in your terminal. To GDB, type:
quit
*crosses fingers*
On Fri, Jan 30, 2015 at 2:50 PM, Cyd Haselton <chaselton at gmail.com> wrote:
> 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/
>
--
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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