Possible NULL-pointer dereference in faulthandler_user #96652
Description
Crash report
Segmentation fault occurs whenever test_socketserver suite takes more than 60 seconds on a system with HAVE_SIGACTION undefined.
To reproduce the issue:
- Replace
#define HAVE_SIGACTION 1with#undef HAVE_SIGACTIONinpyconfig.h. - Add an artificial 1 second delay on every iteration of the
forloop intest_tcpserver_bind_leak(Lib/test/test_socketserver.py):
def test_tcpserver_bind_leak(self): ... import time for i in range(1024): time.sleep(1) with self.assertRaises(OverflowError): .... - Rebuild
CPythonwithmake. - Run
test_socketservertest suite withmake test TESTOPTS="-j1 -v test_socketserver".
Once 60-seconds alarm set in SocketServerTest::setUp goes off, SIGALRM handler (i.e. faulthandler_user) gets called, prints Python's traceback (via faulthandler_dump_traceback) and crashes while calling user->previous that is NULL.
Error messages
test_tcpserver_bind_leak (test.test_socketserver.SocketServerTest.test_tcpserver_bind_leak) ... Current thread 0x00007fa77c504740 (most recent call first): File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/test_socketserver.py", line 294 in test_tcpserver_bind_leak File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/case.py", line 579 in _callTestMethod File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/case.py", line 623 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/case.py", line 678 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 122 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 84 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 122 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 84 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 122 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 84 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/runner.py", line 208 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/support/__init__.py", line 1100 in _run_suite File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/support/__init__.py", line 1226 in run_unittest File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 281 in _test_module File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 317 in _runtest_inner2 File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 360 in _runtest_inner File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 235 in _runtest File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 265 in runtest File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest_mp.py", line 95 in run_tests_worker File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 722 in _main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 701 in main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 763 in main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/regrtest.py", line 43 in _main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/regrtest.py", line 47 in <module> File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/runpy.py", line 88 in _run_code File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/runpy.py", line 198 in _run_module_as_main Fatal Python error: Segmentation fault Current thread 0x00007f80ee8d0740 (most recent call first): File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/test_socketserver.py", line 294 in test_tcpserver_bind_leak File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/case.py", line 579 in _callTestMethod File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/case.py", line 623 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/case.py", line 678 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 122 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 84 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 122 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 84 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 122 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/suite.py", line 84 in __call__ File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/unittest/runner.py", line 208 in run File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/support/__init__.py", line 1100 in _run_suite File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/support/__init__.py", line 1226 in run_unittest File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 281 in _test_module File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 317 in _runtest_inner2 File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 360 in _runtest_inner File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 235 in _runtest File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/runtest.py", line 265 in runtest File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 347 in rerun_failed_tests File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 746 in _main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 701 in main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/libregrtest/main.py", line 763 in main File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/test/__main__.py", line 2 in <module> File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/runpy.py", line 88 in _run_code File "/home/vitalii/Projects/CPython/ovchinnikov-v-a-cpython/Lib/runpy.py", line 198 in _run_module_as_main Extension modules: _testcapi (total: 1) make: *** [Makefile:1828: test] Segmentation fault (core dumped) Your environment
CPython built from sources: main dde15f5879 [origin/main] gh-94808: Improve coverage of _PyBytes_FormatEx (GH-95895)
Operating system and architecture: Linux 5.15.0-46-generic #49-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux