mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-04 08:59:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 11

[3.12] gh-108987: Fix _thread.start_new_thread() race condition (#109135) (#110342)

Browse source 
* gh-108987: Fix _thread.start_new_thread() race condition (#109135)

Fix _thread.start_new_thread() race condition. If a thread is created
during Python finalization, the newly spawned thread now exits
immediately instead of trying to access freed memory and lead to a
crash.

thread_run() calls PyEval_AcquireThread() which checks if the thread
must exit. The problem was that tstate was dereferenced earlier in
_PyThreadState_Bind() which leads to a crash most of the time.

Move _PyThreadState_CheckConsistency() from thread_run() to
_PyThreadState_Bind().

(cherry picked from commit 517cd82ea7)

* gh-109795: `_thread.start_new_thread`: allocate thread bootstate using raw memory allocator (#109808)

(cherry picked from commit 1b8f2366b3)

---------

Co-authored-by: Radislav Chugunov <52372310+chgnrdv@users.noreply.github.com>
This commit is contained in:
Victor Stinner 2023-10-04 13:20:31 +02:00 • committed by GitHub
parent 1d87465005
commit 4936fa9541
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
5 changed files with 75 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

29
Python/pystate.c
View file

@ -1867,6 +1867,10 @@ PyThreadState_Swap(PyThreadState *newts)
void
_PyThreadState_Bind(PyThreadState *tstate)
{
// gh-104690: If Python is being finalized and PyInterpreterState_Delete()
// was called, tstate becomes a dangling pointer.
assert(_PyThreadState_CheckConsistency(tstate));
bind_tstate(tstate);
// This makes sure there's a gilstate tstate bound
// as soon as possible.
@ -2866,6 +2870,31 @@ _PyThreadState_CheckConsistency(PyThreadState *tstate)
#endif
// Check if a Python thread must exit immediately, rather than taking the GIL
// if Py_Finalize() has been called.
//
// When this function is called by a daemon thread after Py_Finalize() has been
// called, the GIL does no longer exist.
//
// tstate can be a dangling pointer (point to freed memory): only tstate value
// is used, the pointer is not deferenced.
//
// tstate must be non-NULL.
int
_PyThreadState_MustExit(PyThreadState *tstate)
{
/* bpo-39877: Access _PyRuntime directly rather than using
tstate->interp->runtime to support calls from Python daemon threads.
After Py_Finalize() has been called, tstate can be a dangling pointer:
point to PyThreadState freed memory. */
PyThreadState *finalizing = _PyRuntimeState_GetFinalizing(&_PyRuntime);
if (finalizing == NULL) {
finalizing = _PyInterpreterState_GetFinalizing(tstate->interp);
}
return (finalizing != NULL && finalizing != tstate);
}
#ifdef __cplusplus
}
#endif