New submission from Graeme Glass <graemegl...@gmail.com>:
When doing something obviously incorrect (read, wrong/stupid) while calling
libX11.so.6 via ctypes, it causes a Segmentation fault, which in turn cause the
python interpreter to fall over with a Segmentation fault.
My question is, is this the correct behaviour? Should it seg fault or just
throw an exception?
Details below.
graeme@roger:~$ uname -a
Linux roger 3.0.0-15-generic-pae #26-Ubuntu SMP Fri Jan 20 17:07:31 UTC 2012
i686 i686 i386 GNU/Linux
graeme@roger:~$ python
Python 2.7.2+ (default, Oct 4 2011, 20:03:08)
[GCC 4.6.1] on linux2
graeme@roger:~$ python2.6
Python 2.6.7 (r267:88850, Aug 11 2011, 12:16:10)
[GCC 4.6.1] on linux2
## The example code
graeme@roger:~$ cat xtest.py
from ctypes import cdll
dll = cdll.LoadLibrary('libX11.so.6')
d = dll.XOpenDisplay(None)
root = dll.XDefaultRootWindow(d)
dll.XWarpPointer(d,None,root,0,0,0,0,20,39)
dll.XCloseDisplay(d)
dll.XCloseDisplay(d) #2nd call, should not be called, is not needed. Causes seg
fault.
##The results
graeme@roger:~$ pdb2.7 xtest.py
> /home/graeme/xtest.py(1)<module>()
-> from ctypes import cdll
(Pdb) c
Segmentation fault
graeme@roger:~$ python2.7 xtest.py
Segmentation fault
graeme@roger:~$ ipython-2.7 xtest.py
Segmentation fault
graeme@roger:~$ ipython-2.6 xtest.py
Segmentation fault
graeme@roger:~$ gdb python2.7
(gdb) set args xtest.py
(gdb) run
Starting program: /usr/bin/python xtest.py
[Thread debugging using libthread_db enabled]
Program received signal SIGSEGV, Segmentation fault.
__GI___libc_free (mem=0x151) at malloc.c:3709
3709 malloc.c: No such file or directory.
in malloc.c
graeme@roger:~$ python2.6 xtest.py
*** glibc detected *** python2.6: double free or corruption (!prev): 0x083533a0
***
======= Backtrace: =========
/lib/i386-linux-gnu/libc.so.6(+0x6ebc2)[0xb7402bc2]
/lib/i386-linux-gnu/libc.so.6(+0x6f862)[0xb7403862]
/lib/i386-linux-gnu/libc.so.6(cfree+0x6d)[0xb740694d]
/usr/lib/i386-linux-gnu/libX11.so.6(+0x9232b)[0xb6ff732b]
/usr/lib/i386-linux-gnu/libX11.so.6(_XFreeDisplayStructure+0x16f)[0xb6f8bddf]
/usr/lib/i386-linux-gnu/libX11.so.6(XCloseDisplay+0xd9)[0xb6f78179]
/usr/lib/python2.6/lib-dynload/_ctypes.so(ffi_call_SYSV+0x1a)[0xb70c548a]
/usr/lib/python2.6/lib-dynload/_ctypes.so(ffi_call+0x6f)[0xb70c51bf]
/usr/lib/python2.6/lib-dynload/_ctypes.so(_CallProc+0x2c2)[0xb70bfd12]
/usr/lib/python2.6/lib-dynload/_ctypes.so(+0x61ed)[0xb70b71ed]
python2.6(PyObject_Call+0x4d)[0x80648cd]
python2.6(PyEval_EvalFrameEx+0x3984)[0x80d6514]
python2.6(PyEval_EvalCodeEx+0x882)[0x80d96e2]
python2.6(PyEval_EvalCode+0x57)[0x80d97e7]
python2.6(PyRun_FileExFlags+0xa6)[0x80f8b26]
python2.6(PyRun_SimpleFileExFlags+0xc6)[0x80f98b6]
python2.6(Py_Main+0xa49)[0x805be59]
python2.6(main+0x1b)[0x805affb]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb73ad113]
python2.6[0x805b021]
======= Memory map: ========
08048000-08255000 r-xp 00000000 08:06 4459238 /usr/bin/python2.6
08255000-08256000 r--p 0020c000 08:06 4459238 /usr/bin/python2.6
08256000-082a5000 rw-p 0020d000 08:06 4459238 /usr/bin/python2.6
082a5000-082ae000 rw-p 00000000 00:00 0
082d2000-08374000 rw-p 00000000 00:00 0 [heap]
b6e00000-b6e21000 rw-p 00000000 00:00 0
b6e21000-b6f00000 ---p 00000000 00:00 0
b6f28000-b6f44000 r-xp 00000000 08:06 2097174
/lib/i386-linux-gnu/libgcc_s.so.1
b6f44000-b6f45000 r--p 0001b000 08:06 2097174
/lib/i386-linux-gnu/libgcc_s.so.1
b6f45000-b6f46000 rw-p 0001c000 08:06 2097174
/lib/i386-linux-gnu/libgcc_s.so.1
b6f46000-b6f63000 r-xp 00000000 08:06 4458588
/usr/lib/i386-linux-gnu/libxcb.so.1.1.0
b6f63000-b6f64000 r--p 0001c000 08:06 4458588
/usr/lib/i386-linux-gnu/libxcb.so.1.1.0
b6f64000-b6f65000 rw-p 0001d000 08:06 4458588
/usr/lib/i386-linux-gnu/libxcb.so.1.1.0
b6f65000-b7096000 r-xp 00000000 08:06 4458582
/usr/lib/i386-linux-gnu/libX11.so.6.3.0
b7096000-b7097000 ---p 00131000 08:06 4458582
/usr/lib/i386-linux-gnu/libX11.so.6.3.0
b7097000-b7098000 r--p 00131000 08:06 4458582
/usr/lib/i386-linux-gnu/libX11.so.6.3.0
b7098000-b709a000 rw-p 00132000 08:06 4458582
/usr/lib/i386-linux-gnu/libX11.so.6.3.0
b709a000-b709b000 rw-p 00000000 00:00 0
b70b1000-b70c8000 r-xp 00000000 08:06 3634
/usr/lib/python2.6/lib-dynload/_ctypes.so
b70c8000-b70cb000 r--p 00017000 08:06 3634
/usr/lib/python2.6/lib-dynload/_ctypes.so
b70cb000-b70ce000 rw-p 0001a000 08:06 3634
/usr/lib/python2.6/lib-dynload/_ctypes.so
b70ce000-b710f000 rw-p 00000000 00:00 0
b7110000-b7111000 r--p 00299000 08:06 4464349 /usr/lib/locale/locale-archive
b7111000-b7311000 r--p 00000000 08:06 4464349 /usr/lib/locale/locale-archive
b7311000-b7394000 rw-p 00000000 00:00 0
b7394000-b750a000 r-xp 00000000 08:06 2097561
/lib/i386-linux-gnu/libc-2.13.so
b750a000-b750c000 r--p 00176000 08:06 2097561
/lib/i386-linux-gnu/libc-2.13.so
b750c000-b750d000 rw-p 00178000 08:06 2097561
/lib/i386-linux-gnu/libc-2.13.so
b750d000-b7511000 rw-p 00000000 00:00 0
b7511000-b7539000 r-xp 00000000 08:06 2097567
/lib/i386-linux-gnu/libm-2.13.so
b7539000-b753a000 r--p 00028000 08:06 2097567
/lib/i386-linux-gnu/libm-2.13.so
b753a000-b753b000 rw-p 00029000 08:06 2097567
/lib/i386-linux-gnu/libm-2.13.so
b753b000-b754e000 r-xp 00000000 08:06 2098068
/lib/i386-linux-gnu/libz.so.1.2.3.4
b754e000-b754f000 r--p 00012000 08:06 2098068
/lib/i386-linux-gnu/libz.so.1.2.3.4
b754f000-b7550000 rw-p 00013000 08:06 2098068
/lib/i386-linux-gnu/libz.so.1.2.3.4
b7550000-b76dd000 r-xp 00000000 08:06 2097531
/lib/i386-linux-gnu/libcrypto.so.1.0.0
b76dd000-b76eb000 r--p 0018c000 08:06 2097531
/lib/i386-linux-gnu/libcrypto.so.1.0.0
b76eb000-b76f1000 rw-p 0019a000 08:06 2097531
/lib/i386-linux-gnu/libcrypto.so.1.0.0
b76f1000-b76f4000 rw-p 00000000 00:00 0
b76f4000-b773c000 r-xp 00000000 08:06 2097532
/lib/i386-linux-gnu/libssl.so.1.0.0
b773c000-b773e000 r--p 00047000 08:06 2097532
/lib/i386-linux-gnu/libssl.so.1.0.0
b773e000-b7741000 rw-p 00049000 08:06 2097532
/lib/i386-linux-gnu/libssl.so.1.0.0
b7741000-b7743000 r-xp 00000000 08:06 2099412
/lib/i386-linux-gnu/libutil-2.13.so
b7743000-b7744000 r--p 00001000 08:06 2099412
/lib/i386-linux-gnu/libutil-2.13.so
b7744000-b7745000 rw-p 00002000 08:06 2099412
/lib/i386-linux-gnu/libutil-2.13.so
b7745000-b7746000 rw-p 00000000 00:00 0
b7746000-b7749000 r-xp 00000000 08:06 2097565
/lib/i386-linux-gnu/libdl-2.13.so
b7749000-b774a000 r--p 00002000 08:06 2097565
/lib/i386-linux-gnu/libdl-2.13.so
b774a000-b774b000 rw-p 00003000 08:06 2097565
/lib/i386-linux-gnu/libdl-2.13.so
b774b000-b7762000 r-xp 00000000 08:06 2099407
/lib/i386-linux-gnu/libpthread-2.13.so
b7762000-b7763000 r--p 00016000 08:06 2099407
/lib/i386-linux-gnu/libpthread-2.13.so
b7763000-b7764000 rw-p 00017000 08:06 2099407
/lib/i386-linux-gnu/libpthread-2.13.so
b7764000-b7766000 rw-p 00000000 00:00 0
b7770000-b7775000 r-xp 00000000 08:06 4458586
/usr/lib/i386-linux-gnu/libXdmcp.so.6.0.0
b7775000-b7776000 r--p 00004000 08:06 4458586
/usr/lib/i386-linux-gnu/libXdmcp.so.6.0.0
b7776000-b7777000 rw-p 00005000 08:06 4458586
/usr/lib/i386-linux-gnu/libXdmcp.so.6.0.0
b7777000-b7779000 r-xp 00000000 08:06 4458584
/usr/lib/i386-linux-gnu/libXau.so.6.0.0
b7779000-b777a000 r--p 00001000 08:06 4458584
/usr/lib/i386-linux-gnu/libXau.so.6.0.0
b777a000-b777b000 rw-p 00002000 08:06 4458584
/usr/lib/i386-linux-gnu/libXau.so.6.0.0
b777b000-b777c000 rwxp 00000000 00:00 0
b777c000-b777e000 rw-p 00000000 00:00 0
b777e000-b777f000 r-xp 00000000 00:00 0 [vdso]
b777f000-b779d000 r-xp 00000000 08:06 2097504 /lib/i386-linux-gnu/ld-2.13.so
b779d000-b779e000 r--p 0001d000 08:06 2097504 /lib/i386-linux-gnu/ld-2.13.so
b779e000-b779f000 rw-p 0001e000 08:06 2097504 /lib/i386-linux-gnu/ld-2.13.so
bfb52000-bfb73000 rw-p 00000000 00:00 0 [stack]
Aborted
----------
components: ctypes
messages: 152735
nosy: graemeglass
priority: normal
severity: normal
status: open
title: Seg Fault in .so called by ctypes causes the interpreter to Seg Fault
type: crash
versions: Python 2.6, Python 2.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue13951>
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