[ python-Bugs-1579370 ] Segfault provoked by generators and exceptions

Wed Oct 18 04:23:46 CEST 2006

Bugs item #1579370, was opened at 2006-10-17 19:23
Message generated for change (Comment added) made by mklaas
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Category: Python Interpreter Core
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Mike Klaas (mklaas)
Assigned to: Nobody/Anonymous (nobody)
Summary: Segfault provoked by generators and exceptions

Initial Comment:
A reproducible segfault when using heavily-nested
generators and exceptions.

Unfortunately, I haven't yet been able to provoke this
behaviour with a standalone python2.5 script.  There
are, however, no third-party c extensions running in
the process so I'm fairly confident that it is a
problem in the core.

The gist of the code is a series of nested generators
which leave scope when an exception is raised.  This
exception is caught and re-raised in an outer loop. 
The old exception was holding on to the frame which was
keeping the generators alive, and the sequence of
generator destruction and new finalization caused the
segfault.   

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>Comment By: Mike Klaas (mklaas)
Date: 2006-10-17 19:23

Message:
Logged In: YES 
user_id=1611720

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1208400192 (LWP 26235)]
0x080e4296 in PyTraceBack_Here (frame=0x9c2d7b4) at
Python/traceback.c:94
94              if ((next != NULL &&
!PyTraceBack_Check(next)) ||
(gdb) bt
#0  0x080e4296 in PyTraceBack_Here (frame=0x9c2d7b4) at
Python/traceback.c:94
#1  0x080b9ab7 in PyEval_EvalFrameEx (f=0x9c2d7b4,
throwflag=1) at Python/ceval.c:2459
#2  0x08101a40 in gen_send_ex (gen=0xb64f880c,
arg=0x81333e0, exc=1) at Objects/genobject.c:82
#3  0x08101c0f in gen_close (gen=0xb64f880c, args=0x0) at
Objects/genobject.c:128
#4  0x08101cde in gen_del (self=0xb64f880c) at
Objects/genobject.c:163
#5  0x0810195b in gen_dealloc (gen=0xb64f880c) at
Objects/genobject.c:31
#6  0x080b9912 in PyEval_EvalFrameEx (f=0x9c2802c,
throwflag=1) at Python/ceval.c:2491
#7  0x08101a40 in gen_send_ex (gen=0xb64f362c,
arg=0x81333e0, exc=1) at Objects/genobject.c:82
#8  0x08101c0f in gen_close (gen=0xb64f362c, args=0x0) at
Objects/genobject.c:128
#9  0x08101cde in gen_del (self=0xb64f362c) at
Objects/genobject.c:163
#10 0x0810195b in gen_dealloc (gen=0xb64f362c) at
Objects/genobject.c:31
#11 0x080815b9 in dict_dealloc (mp=0xb64f4a44) at
Objects/dictobject.c:801
#12 0x080927b2 in subtype_dealloc (self=0xb64f340c) at
Objects/typeobject.c:686
#13 0x0806028d in instancemethod_dealloc (im=0xb796a0cc) at
Objects/classobject.c:2285
#14 0x080815b9 in dict_dealloc (mp=0xb64f78ac) at
Objects/dictobject.c:801
#15 0x080927b2 in subtype_dealloc (self=0xb64f810c) at
Objects/typeobject.c:686
#16 0x081028c5 in frame_dealloc (f=0x9c272bc) at
Objects/frameobject.c:416
#17 0x080e41b1 in tb_dealloc (tb=0xb799166c) at
Python/traceback.c:34
#18 0x080e41c2 in tb_dealloc (tb=0xb4071284) at
Python/traceback.c:33
#19 0x080e41c2 in tb_dealloc (tb=0xb7991824) at
Python/traceback.c:33
#20 0x08080dca in insertdict (mp=0xb7f56824, key=0xb3fb9930,
hash=1492466088, value=0xb3fb9914)
    at Objects/dictobject.c:394
#21 0x080811a4 in PyDict_SetItem (op=0xb7f56824,
key=0xb3fb9930, value=0xb3fb9914) at Objects/dictobject.c:619
#22 0x08082dc6 in PyDict_SetItemString (v=0xb7f56824,
key=0x8129284 "exc_traceback", item=0xb3fb9914)
    at Objects/dictobject.c:2103
#23 0x080e2837 in PySys_SetObject (name=0x8129284
"exc_traceback", v=0xb3fb9914) at Python/sysmodule.c:82
#24 0x080bc9e5 in PyEval_EvalFrameEx (f=0x9c10e7c,
throwflag=0) at Python/ceval.c:2954
#25 0x080bfda3 in PyEval_EvalCodeEx (co=0xb7bbc890,
globals=0xb7bbe57c, locals=0x0, args=0x9b8e2ac, argcount=1,
    kws=0x9b8e2b0, kwcount=0, defs=0xb7b7aed8, defcount=1,
closure=0x0) at Python/ceval.c:2833
#26 0x080bd62a in PyEval_EvalFrameEx (f=0x9b8e16c,
throwflag=0) at Python/ceval.c:3662
#27 0x080bfda3 in PyEval_EvalCodeEx (co=0xb7bbc848,
globals=0xb7bbe57c, locals=0x0, args=0xb7af9d58, argcount=1,
    kws=0x9b7a818, kwcount=0, defs=0x0, defcount=0,
closure=0x0) at Python/ceval.c:2833
#28 0x08104083 in function_call (func=0xb7b79c34,
arg=0xb7af9d4c, kw=0xb7962c64) at Objects/funcobject.c:517
#29 0x0805a660 in PyObject_Call (func=0xb7b79c34,
arg=0xb7af9d4c, kw=0xb7962c64) at Objects/abstract.c:1860
#30 0x080bcb4b in PyEval_EvalFrameEx (f=0x9b82c0c,
throwflag=0) at Python/ceval.c:3846
#31 0x080bfda3 in PyEval_EvalCodeEx (co=0xb7cd6608,
globals=0xb7cd4934, locals=0x0, args=0x9b7765c, argcount=2,
    kws=0x9b77664, kwcount=0, defs=0x0, defcount=0,
closure=0xb7cfe874) at Python/ceval.c:2833
#32 0x080bd62a in PyEval_EvalFrameEx (f=0x9b7751c,
throwflag=0) at Python/ceval.c:3662
#33 0x080bdf70 in PyEval_EvalFrameEx (f=0x9a9646c,
throwflag=0) at Python/ceval.c:3652
#34 0x080bfda3 in PyEval_EvalCodeEx (co=0xb7f39728,
globals=0xb7f6ca44, locals=0x0, args=0x9b7a00c, argcount=0,
    kws=0x9b7a00c, kwcount=0, defs=0x0, defcount=0,
closure=0xb796410c) at Python/ceval.c:2833
#35 0x080bd62a in PyEval_EvalFrameEx (f=0x9b79ebc,
throwflag=0) at Python/ceval.c:3662
#36 0x080bfda3 in PyEval_EvalCodeEx (co=0xb7f39770,
globals=0xb7f6ca44, locals=0x0, args=0x99086c0, argcount=0,
    kws=0x99086c0, kwcount=0, defs=0x0, defcount=0,
closure=0x0) at Python/ceval.c:2833
#37 0x080bd62a in PyEval_EvalFrameEx (f=0x9908584,
throwflag=0) at Python/ceval.c:3662
#38 0x080bfda3 in PyEval_EvalCodeEx (co=0xb7f397b8,
globals=0xb7f6ca44, locals=0xb7f6ca44, args=0x0, argcount=0,
    kws=0x0, kwcount=0, defs=0x0, defcount=0, closure=0x0)
at Python/ceval.c:2833
---Type <return> to continue, or q <return> to quit---
#39 0x080bff32 in PyEval_EvalCode (co=0xb7f397b8,
globals=0xb7f6ca44, locals=0xb7f6ca44) at Python/ceval.c:494
#40 0x080ddff1 in PyRun_FileExFlags (fp=0x98a4008,
filename=0xbfffd4a3 "scoreserver.py", start=257,
    globals=0xb7f6ca44, locals=0xb7f6ca44, closeit=1,
flags=0xbfffd298) at Python/pythonrun.c:1264
#41 0x080de321 in PyRun_SimpleFileExFlags (fp=Variable "fp"
is not available.
) at Python/pythonrun.c:870
#42 0x08056ac4 in Py_Main (argc=1, argv=0xbfffd334) at
Modules/main.c:496
#43 0x00a69d5f in __libc_start_main () from /lib/libc.so.6
#44 0x08056051 in _start ()

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