| msg285921 - (view) |
Author: Zach Riggle (Zach Riggle) |
Date: 2017-01-20 20:48 |
| The attached script hits some "This should never happen" code in the subprocess module. These lines here: https://github.com/python/cpython/blob/2.7/Lib/subprocess.py#L1036-L1038 The root cause is a lack of checking WIFSTOPPED and WSTOPSIG in the handler. When a process elects into being ptraced via PTRACE_TRACEME, it is stopped on the SIGSEGV instead of terminating, allowing the user to attach a debugger before the kernel destroys the process. This bug makes it impossible to wait on any process which crashes, which is set up to wait for a debugger. |
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| msg285996 - (view) |
Author: Zach Riggle (Zach Riggle) |
Date: 2017-01-22 06:53 |
| To further clarify the report: When the attached proof-of-concept is executed, a RuntimeException is raised, which has a comment "Should never happen". The issue isn't due to SIGCHLD, but rather following a waitpid() call. The code attempts to suss the exit code / reason for waitpid() returning, but does not check for WIFSTOPPED in its handler. |
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| msg286023 - (view) |
Author: Gregory P. Smith (gregory.p.smith) *  |
Date: 2017-01-22 18:27 |
| The attached patch should fix it. I want to incorporate a bug.py like regression test into test_subprocess.py. |
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| msg286031 - (view) |
Author: Gregory P. Smith (gregory.p.smith) * |
Date: 2017-01-22 21:21 |
| test added. |
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| msg286036 - (view) |
Author: Roundup Robot (python-dev)  |
Date: 2017-01-23 01:30 |
| New changeset 269296b2a047 by Gregory P. Smith in branch '3.5': Issue #29335: Fix subprocess.Popen.wait() when the child process has https://hg.python.org/cpython/rev/269296b2a047 New changeset ed5255a61648 by Gregory P. Smith in branch '3.6': Issue #29335: Fix subprocess.Popen.wait() when the child process has https://hg.python.org/cpython/rev/ed5255a61648 New changeset 4f5e7d018195 by Gregory P. Smith in branch 'default': Issue #29335: Fix subprocess.Popen.wait() when the child process has https://hg.python.org/cpython/rev/4f5e7d018195 |
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| msg286046 - (view) |
Author: Ned Deily (ned.deily) * |
Date: 2017-01-23 04:25 |
| Among other buildbot failures: http://buildbot.python.org/all/builders/x86%20Tiger%203.6/builds/142/steps/test/logs/stdio ====================================================================== ERROR: test_child_terminated_in_stopped_state (test.test_subprocess.POSIXProcessTestCase) Test wait() behavior when waitpid returns WIFSTOPPED; . ---------------------------------------------------------------------- Traceback (most recent call last): File "/Users/db3l/buildarea/3.6.bolen-tiger/build/Lib/test/test_subprocess.py", line 2514, in test_child_terminated_in_stopped_state libc = ctypes.CDLL(libc_name) File "/Users/db3l/buildarea/3.6.bolen-tiger/build/Lib/ctypes/__init__.py", line 348, in __init__ self._handle = _dlopen(self._name, mode) OSError: dlopen(libc..dylib, 6): image not found ---------------------------------------------------------------------- Ran 260 tests in 102.297s Also, http://buildbot.python.org/all/builders/x86%20Ubuntu%20Shared%203.x/builds/240/steps/test/logs/stdio |
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| msg286050 - (view) |
Author: Roundup Robot (python-dev) |
Date: 2017-01-23 06:38 |
| New changeset 8e3d412f8e89 by Gregory P. Smith in branch '2.7': Issue #29335: Fix subprocess.Popen.wait() when the child process has https://hg.python.org/cpython/rev/8e3d412f8e89 |
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| msg286057 - (view) |
Author: Gregory P. Smith (gregory.p.smith) * |
Date: 2017-01-23 07:54 |
| thanks Ned, I was awaiting interesting buildbot results. :) fixed in 2.7 and 3.5 onwards. thanks for the report Zach. not closing until I also apply the fix to the subprocess32 backport. |
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| msg286099 - (view) |
Author: Zach Riggle (Zach Riggle) |
Date: 2017-01-23 16:52 |
| Of note, there's no need to actually cause a SIGSEGV to generate the signal. The tests might be more clear to replace: libc.printf(ctypes.c_char_p(0xdeadbeef)) with os.kill(os.getpid(), signal.SIGSEGV) |
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| msg286100 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-01-23 16:57 |
| If you want crashes, look at the portable faulthandler._sigsegv() :-) |
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| msg286102 - (view) |
Author: Zach Riggle (Zach Riggle) |
Date: 2017-01-23 17:21 |
| Neat, though that's not in the standard library. The current logic for getting a handle to libc could also be simplified via ctypes.util.find_library (https://docs.python.org/3/library/ctypes.html#finding-shared-libraries). Darwin: >>> import ctypes.util >>> ctypes.util.find_library('c') '/usr/lib/libc.dylib' Linux: >>> import ctypes.util >>> ctypes.util.find_library('c') 'libc.so.6' |
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| msg294251 - (view) |
Author: Gregory P. Smith (gregory.p.smith) * |
Date: 2017-05-23 14:49 |
| New changeset 56bc3b768c3cc3817031b56d5e7a279aa1296bc9 by Gregory P. Smith in branch 'master': bpo-29335 - apply suggested test_subprocess simplifications from haypo and Zach: (#1757) https://github.com/python/cpython/commit/56bc3b768c3cc3817031b56d5e7a279aa1296bc9 |
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| msg294308 - (view) |
Author: Gregory P. Smith (gregory.p.smith) * |
Date: 2017-05-24 01:36 |
| Fixed applied to subprocess32 in https://github.com/google/python-subprocess32/commit/0f1958e982bf44db569470def7281bcafa2a8b0e |
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| msg296907 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-06-26 15:23 |
| New changeset cdee3f14f7f4c995e7eedb0bf6a67e260c739f7d by Victor Stinner in branch 'master': bpo-30764: test_subprocess uses SuppressCrashReport (#2405) https://github.com/python/cpython/commit/cdee3f14f7f4c995e7eedb0bf6a67e260c739f7d |
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| msg296910 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-06-26 16:05 |
| New changeset 849b062a82ca2f09e33259d34067faba196c9e23 by Victor Stinner in branch '3.5': bpo-30764: test_subprocess uses SuppressCrashReport (#2405) (#2411) https://github.com/python/cpython/commit/849b062a82ca2f09e33259d34067faba196c9e23 |
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| msg296957 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-06-26 22:00 |
| New changeset 9ad50d94599aed0c37beaf78948ec271c8aa3881 by Victor Stinner in branch '3.6': bpo-30764: test_subprocess uses SuppressCrashReport (#2405) (#2410) https://github.com/python/cpython/commit/9ad50d94599aed0c37beaf78948ec271c8aa3881 |
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| msg296959 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-06-26 22:00 |
| New changeset 2097b9e0ef32ab7a0d745edc0f707c615780c006 by Victor Stinner in branch '2.7': [2.7] bpo-30764: test_subprocess uses SuppressCrashReport (#2405) (#2412) https://github.com/python/cpython/commit/2097b9e0ef32ab7a0d745edc0f707c615780c006 |
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