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Backport r60148 and r65481: sanity checks to avoid infinite loops.

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This commit is contained in:
Georg Brandl 2008-08-12 08:46:02 +00:00
parent 1576bab042
commit 032215451b
2 changed files with 25 additions and 1 deletions
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14
Python/pystate.c
View file

@ -240,6 +240,7 @@ tstate_delete_common(PyThreadState *tstate)
{ {
PyInterpreterState *interp; PyInterpreterState *interp;
PyThreadState **p; PyThreadState **p;
PyThreadState *prev_p = NULL;
if (tstate == NULL) if (tstate == NULL)
Py_FatalError("PyThreadState_Delete: NULL tstate"); Py_FatalError("PyThreadState_Delete: NULL tstate");
interp = tstate->interp; interp = tstate->interp;
@ -252,6 +253,19 @@ tstate_delete_common(PyThreadState *tstate)
"PyThreadState_Delete: invalid tstate"); "PyThreadState_Delete: invalid tstate");
if (*p == tstate) if (*p == tstate)
break; break;
/* Sanity check. These states should never happen but if
* they do we must abort. Otherwise we'll end up spinning in
* in a tight loop with the lock held. A similar check is done
* in thread.c find_key(). */
if (*p == prev_p)
Py_FatalError(
"PyThreadState_Delete: small circular list(!)"
" and tstate not found.");
prev_p = *p;
if ((*p)->next == interp->tstate_head)
Py_FatalError(
"PyThreadState_Delete: circular list(!) and"
" tstate not found.");
} }
*p = tstate->next; *p = tstate->next;
HEAD_UNLOCK(); HEAD_UNLOCK();

12
Python/thread.c
View file

@ -264,15 +264,25 @@ static int nkeys = 0; /* PyThread_create_key() hands out nkeys+1 next */
static struct key * static struct key *
find_key(int key, void *value) find_key(int key, void *value)
{ {
struct key *p; struct key *p, *prev_p;
long id = PyThread_get_thread_ident(); long id = PyThread_get_thread_ident();
if (!keymutex) if (!keymutex)
return NULL; return NULL;
PyThread_acquire_lock(keymutex, 1); PyThread_acquire_lock(keymutex, 1);
prev_p = NULL;
for (p = keyhead; p != NULL; p = p->next) { for (p = keyhead; p != NULL; p = p->next) {
if (p->id == id && p->key == key) if (p->id == id && p->key == key)
goto Done; goto Done;
/* Sanity check. These states should never happen but if
* they do we must abort. Otherwise we'll end up spinning in
* in a tight loop with the lock held. A similar check is done
* in pystate.c tstate_delete_common(). */
if (p == prev_p)
Py_FatalError("tls find_key: small circular list(!)");
prev_p = p;
if (p->next == keyhead)
Py_FatalError("tls find_key: circular list(!)");
} }
if (value == NULL) { if (value == NULL) {
assert(p == NULL); assert(p == NULL);