Title: gh-148820: Fix _PyRawMutex use-after-free on spurious semaphore wakeup by colesbury · Pull Request #148852 · python/cpython · GitHub
Open Graph Title: gh-148820: Fix _PyRawMutex use-after-free on spurious semaphore wakeup by colesbury · Pull Request #148852 · python/cpython
X Title: gh-148820: Fix _PyRawMutex use-after-free on spurious semaphore wakeup by colesbury · Pull Request #148852 · python/cpython
Description: _PyRawMutex_UnlockSlow CAS-removes the waiter from the list and then calls _PySemaphore_Wakeup, with no handshake. If _PySemaphore_Wait returns Py_PARK_INTR, the waiter can destroy its stack-allocated semaphore before the unlocker's Wakeup runs, causing a fatal error from ReleaseSemaphore / sem_post. Loop in _PyRawMutex_LockSlow until _PySemaphore_Wait returns Py_PARK_OK, which is only signalled when a matching Wakeup has been observed. Also include GetLastError() and the handle in the Windows fatal messages in _PySemaphore_Init, _PySemaphore_Wait, and _PySemaphore_Wakeup to make similar races easier to diagnose in the future. Issue: gh-148820
Open Graph Description: _PyRawMutex_UnlockSlow CAS-removes the waiter from the list and then calls _PySemaphore_Wakeup, with no handshake. If _PySemaphore_Wait returns Py_PARK_INTR, the waiter can destroy its stack-alloca...
X Description: _PyRawMutex_UnlockSlow CAS-removes the waiter from the list and then calls _PySemaphore_Wakeup, with no handshake. If _PySemaphore_Wait returns Py_PARK_INTR, the waiter can destroy its stack-alloca...
Opengraph URL: https://github.com/python/cpython/pull/148852
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| og:image:alt | _PyRawMutex_UnlockSlow CAS-removes the waiter from the list and then calls _PySemaphore_Wakeup, with no handshake. If _PySemaphore_Wait returns Py_PARK_INTR, the waiter can destroy its stack-alloca... |
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