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bpo-33015: Fix UB in pthread PyThread_start_new_thread (GH-6008) 

Fix an undefined behaviour in the pthread implementation of
PyThread_start_new_thread(): add a function wrapper to always return
NULL.

Add pythread_callback struct and pythread_wrapper() to thread_pthread.h.
(cherry picked from commit 9eea6eaf23)

Co-authored-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
This commit is contained in:
Miss Islington (bot) 2018-11-30 07:32:12 -08:00 committed by GitHub
parent 365f21c2d3
commit b1355352d1
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 39 additions and 4 deletions
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3
Misc/NEWS.d/next/Build/2018-08-24-09-48-25.bpo-33015.s21y74.rst Normal file
View File

@ -0,0 +1,3 @@
Fix an undefined behaviour in the pthread implementation of
:c:func:`PyThread_start_new_thread`: add a function wrapper to always return
``NULL``.

40
Python/thread_pthread.h
View File

@ -152,6 +152,28 @@ PyThread__init_thread(void)
* Thread support.
*/
/* bpo-33015: pythread_callback struct and pythread_wrapper() cast
"void func(void *)" to "void* func(void *)": always return NULL.
PyThread_start_new_thread() uses "void func(void *)" type, whereas
pthread_create() requires a void* return value. */
typedef struct {
void (*func) (void *);
void *arg;
} pythread_callback;
static void *
pythread_wrapper(void *arg)
{
/* copy func and func_arg and free the temporary structure */
pythread_callback *callback = arg;
void (*func)(void *) = callback->func;
void *func_arg = callback->arg;
PyMem_RawFree(arg);
func(func_arg);
return NULL;
}
unsigned long
PyThread_start_new_thread(void (*func)(void *), void *arg)
@ -188,21 +210,31 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
pthread_attr_setscope(&attrs, PTHREAD_SCOPE_SYSTEM);
#endif
pythread_callback *callback = PyMem_RawMalloc(sizeof(pythread_callback));
if (callback == NULL) {
return PYTHREAD_INVALID_THREAD_ID;
}
callback->func = func;
callback->arg = arg;
status = pthread_create(&th,
#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
&attrs,
#else
(pthread_attr_t*)NULL,
#endif
(void* (*)(void *))func,
(void *)arg
);
pythread_wrapper, callback);
#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
pthread_attr_destroy(&attrs);
#endif
if (status != 0)
if (status != 0) {
PyMem_RawFree(callback);
return PYTHREAD_INVALID_THREAD_ID;
}
pthread_detach(th);