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TSan: data race accessing socket fd #116912

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TSan: data race accessing socket fd#116912
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extension-modulesC modules in the Modules dirtestsTests in the Lib/test dirtopic-free-threadingtype-bugAn unexpected behavior, bug, or error

Description

@pitrou
pitrou
opened on Mar 16, 2024

Bug report

Bug description:

The sock_fd member in PySocketSockObject can be mutated while the socket is being used, for example when calling socket.close or socket.detach. However, some other threads can access that member without holding the GIL, and without using atomic instructions. This can trip up Thread Sanitizer in test_asyncio, for example:

0:00:31 load avg: 3.29 [15/52/1] test_asyncio.test_sock_lowlevel worker non-zero exit code (Exit code 66)
==================
WARNING: ThreadSanitizer: data race (pid=7227)
  Write of size 4 at 0x7fd903611570 by thread T19:
    #0 sock_close /home/runner/work/cpython/cpython/./Modules/socketmodule.c:3339:20 (_socket.cpython-313d-x86_64-linux-gnu.so+0xdbde) (BuildId: 7a12da96172d453cd023792c027755908db49f4e)
[...]

  Previous read of size 4 at 0x7fd903611570 by main thread:
    #0 sock_sendto_impl /home/runner/work/cpython/cpython/./Modules/socketmodule.c:4474:29 (_socket.cpython-313d-x86_64-linux-gnu.so+0x131e5) (BuildId: 7a12da96172d453cd023792c027755908db49f4e)
    #1 sock_call_ex /home/runner/work/cpython/cpython/./Modules/socketmodule.c:968:19 (_socket.cpython-313d-x86_64-linux-gnu.so+0x10fa1) (BuildId: 7a12da96172d453cd023792c027755908db49f4e)
    #2 sock_call /home/runner/work/cpython/cpython/./Modules/socketmodule.c:1020:12 (_socket.cpython-313d-x86_64-linux-gnu.so+0xf1a1) (BuildId: 7a12da96172d453cd023792c027755908db49f4e)
    #3 sock_sendto /home/runner/work/cpython/cpython/./Modules/socketmodule.c:4532:9 (_socket.cpython-313d-x86_64-linux-gnu.so+0xf1a1)
[...]

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Activity

  1. pitrou
    added
    type-bugAn unexpected behavior, bug, or error
    testsTests in the Lib/test dir
    on Mar 16, 2024
  2. pitrou
    changed the title [-]TSan: data race access socket fd[/-] [+]TSan: data race accessing socket fd[/+] on Mar 16, 2024

  3. pitrou commented on Mar 16, 2024

    @pitrou
    pitrou
    on Mar 16, 2024
    MemberAuthor

    @colesbury @gpshead @mpage @erlend-aasland

  4. pitrou
    added
    extension-modulesC modules in the Modules dir
    on Mar 16, 2024
  5. erlend-aasland
    added
    topic-free-threading
    on Apr 4, 2024
  6. python
    deleted a comment from Davidzcdn on Jul 10, 2024
  7. python
    deleted a comment from Davidzcdn on Jul 10, 2024

  8. corona10 commented on Oct 3, 2024

    @corona10
    corona10
    on Oct 3, 2024
    Member

    It happens from https://github.com/python/cpython/actions/runs/11160718143/job/31021782828?pr=124914 too
    Maybe worth to fix it.

  9. corona10 commented on Oct 3, 2024

    @corona10
    corona10
    on Oct 3, 2024
    Member
     ==================
WARNING: ThreadSanitizer: data race (pid=11811)
  Write of size 4 at 0x7f788e470220 by main thread:
    #0 _socket_socket_close_impl /home/runner/work/cpython/cpython/./Modules/socketmodule.c:3369:20 (_socket.cpython-314td-x86_64-linux-gnu.so+0xe6fa) (BuildId: fd621939d2f906d64ec9d9113f22b21082c40173)
    #1 _socket_socket_close /home/runner/work/cpython/cpython/./Modules/clinic/socketmodule.c.h:32:20 (_socket.cpython-314td-x86_64-linux-gnu.so+0xe6fa)
    #2 method_vectorcall_NOARGS /home/runner/work/cpython/cpython/Objects/descrobject.c:447:24 (python+0x27d040) (BuildId: f4b70dfbd84ba1a7db1e594342dc691a3ebbd7b7)
    #3 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:167:11 (python+0x261c31) (BuildId: f4b70dfbd84ba1a7db1e594342dc691a3ebbd7b7)
    #4 PyObject_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c:327:12 (python+0x263730) (BuildId: f4b70dfbd84ba1a7db1e594342dc691a3ebbd7b7)

  10. kumaraditya303 commented on Jan 1, 2025

    @kumaraditya303
    kumaraditya303
    on Jan 1, 2025
    Contributor

    Superseded by #128277

  11. kumaraditya303
    closed this as completedon Jan 1, 2025
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