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SegFault before Python shutdown #1683
Description
Environment
- Pythonnet version: 3.0.0.dev1
- Python version: 3.9.9
- Operating System: Kali Linux
- .NET Runtime:
mono-complete:amd64/kali-rolling 6.8.0.105+dfsg-3.2 uptodate
mono-devel:all/kali-rolling 6.8.0.105+dfsg-3.2
Details
This example causes segfault before python shutdown:
import clr
from System import IntPtr
a = clr.GetClrType(IntPtr)
Actually no matter what type is imported (IntPtr, Console, etc.) - crashing anyway. However, crash happen exactly after the program finished its executing and only when NO debugging.
gef➤ bt
#0 0x0000000040071c50 in ?? ()
#1 0x0000000000508a13 in _Py_Dealloc (op=<optimized out>) at ../Objects/object.c:2209
#2 _Py_DECREF (op=<optimized out>) at ../Include/object.h:430
#3 _Py_XDECREF (op=<optimized out>) at ../Include/object.h:497
#4 free_keys_object (keys=0x11ac070) at ../Objects/dictobject.c:598
#5 0x0000000000508824 in dictkeys_decref (dk=<optimized out>) at ../Objects/dictobject.c:333
#6 dict_dealloc (mp=0x7ffff78671c0) at ../Objects/dictobject.c:2026
#7 0x00000000005a9f60 in _Py_DECREF (op=<optimized out>) at ../Include/object.h:430
#8 _Py_XDECREF (op=<optimized out>) at ../Include/object.h:497
#9 module_dealloc (m=0x7ffff7863cc0) at ../Objects/moduleobject.c:677
#10 0x00000000004f9749 in _Py_Dealloc (op=<optimized out>) at ../Objects/object.c:2209
#11 _Py_DECREF (op=<optimized out>) at ../Include/object.h:430
#12 _Py_XDECREF (op=<optimized out>) at ../Include/object.h:497
#13 insertdict (mp=<optimized out>, key='__main__', hash=<optimized out>, value=<optimized out>) at ../Objects/dictobject.c:1123
#14 0x00000000006294a0 in _PyImport_Cleanup (tstate=0x94e6e0) at ../Python/import.c:526
#15 0x000000000062732f in Py_FinalizeEx () at ../Python/pylifecycle.c:1426
#16 0x000000000061e0c0 in Py_RunMain () at ../Modules/main.c:679
#17 0x0000000000606199 in Py_BytesMain (argc=<optimized out>, argv=<optimized out>) at ../Modules/main.c:731
#18 0x00007ffff7c427ed in __libc_start_main (main=0x606160 <main>, argc=0x2, argv=0x7fffffffde18, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffde08) at ../csu/libc-start.c:332
#19 0x000000000060609a in _start ()
gef➤ xinfo 0x0000000040071c50
[*] Cannot reach 0x40071c50 in memory space
gef➤ xinfo 0x0000000000508a13
Page: 0x000000000041f000 → 0x0000000000690000 (size=0x271000)
Permissions: r-x
Pathname: /usr/bin/python3.9
Offset (from page): 0xe9a13
Inode: 6816263
Segment: .text (0x0000000000420e70-0x000000000068fe11)
Offset (from segment): 0xe7ba3
Symbol: free_keys_object.lto_priv+115
If we add at the end of the script this line, then everything works like a charm:
Environment.Exit(0)
Also works well if we clear variable at the end:
a = None
Reacted by Benedikt Reinartz
Activity
filmor commentedon Jan 28, 2022
I can confirm this issue. After playing around a bit, I found out that this occurs only if the
System.RuntimeTypeinstance that comes back fromGetClrTypeis bound until the end of the program. So the following are not segfaulting:and
MikeFrampton commentedon Feb 14, 2022
Confirm this issue happening for me too on Ubuntu 21.10.
Python version: 3.9.7.
Pythonnet version: 3.0.0a2
I'm not using virtual environment, though if I set my imported dotnet class to
None, the issue goes away. I hope I'm not just shadowing a resource leak here or something.lostmsu commentedon Feb 28, 2022
@filmor I believe this issue happens because
clr_loaderforces Mono shutdown before Python shuts down. While it might make sense if you want to restart the runtime in the same process, I don't think Mono supports that scenario and neither should we.We could hack around it with slots holder stuff, but personally I think this is an overcomplication.
The same probably applies to the other runtimes as well.
lostmsu commentedon Mar 3, 2022
pythonnet/clr-loader#26