Issue #12287: Fix a stack corruption in ossaudiodev module when the FD is

greater than FD_SETSIZE.

Include/fileobject.h

@@ -44,6 +44,13 @@ int _PyVerify_fd(int fd);
 #endif
 #endif /* Py_LIMITED_API */
 
+/* A routine to check if a file descriptor can be select()-ed. */
+#ifdef HAVE_SELECT
+ #define _PyIsSelectable_fd(FD) (((FD) >= 0) && ((FD) < FD_SETSIZE))
+#else
+ #define _PyIsSelectable_fd(FD) (1)
+#endif /* HAVE_SELECT */
+
 #ifdef __cplusplus
 }
 #endif

Misc/NEWS

@@ -22,6 +22,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #12287: Fix a stack corruption in ossaudiodev module when the FD is
+  greater than FD_SETSIZE.
+
 - Issue #12839: Fix crash in zlib module due to version mismatch.
   Fix by Richard M. Tew.
 

Modules/_ssl.c

@@ -1023,10 +1023,8 @@ check_socket_and_wait_for_timeout(PySocketSockObject *s, int writing)
 #endif
 
     /* Guard against socket too large for select*/
-#ifndef Py_SOCKET_FD_CAN_BE_GE_FD_SETSIZE
-    if (s->sock_fd >= FD_SETSIZE)
+    if (!_PyIsSelectable_fd(s->sock_fd))
         return SOCKET_TOO_LARGE_FOR_SELECT;
-#endif
 
     /* Construct the arguments to select */
     tv.tv_sec = (int)s->sock_timeout;

Modules/ossaudiodev.c

@@ -425,6 +425,11 @@ oss_writeall(oss_audio_t *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "y#:write", &cp, &size))
         return NULL;
 
+    if (!_PyIsSelectable_fd(self->fd)) {
+        PyErr_SetString(PyExc_ValueError,
+                        "file descriptor out of range for select");
+        return NULL;
+    }
     /* use select to wait for audio device to be available */
     FD_ZERO(&write_set_fds);
     FD_SET(self->fd, &write_set_fds);

Modules/selectmodule.c

@@ -110,7 +110,7 @@ seq2set(PyObject *seq, fd_set *set, pylist fd2obj[FD_SETSIZE + 1])
 #if defined(_MSC_VER)
         max = 0;                             /* not used for Win32 */
 #else  /* !_MSC_VER */
-        if (v < 0 || v >= FD_SETSIZE) {
+        if (!_PyIsSelectable_fd(v)) {
             PyErr_SetString(PyExc_ValueError,
                         "filedescriptor out of range in select()");
             goto finally;
@@ -160,13 +160,6 @@ set2list(fd_set *set, pylist fd2obj[FD_SETSIZE + 1])
     for (j = 0; fd2obj[j].sentinel >= 0; j++) {
         fd = fd2obj[j].fd;
         if (FD_ISSET(fd, set)) {
-#ifndef _MSC_VER
-            if (fd > FD_SETSIZE) {
-                PyErr_SetString(PyExc_SystemError,
-               "filedescriptor out of range returned in select()");
-                goto finally;
-            }
-#endif
             o = fd2obj[j].obj;
             fd2obj[j].obj = NULL;
             /* transfer ownership */

Modules/socketmodule.c

@@ -455,18 +455,14 @@ static PyTypeObject sock_type;
 #include <sys/poll.h>
 #endif
 
-#ifdef Py_SOCKET_FD_CAN_BE_GE_FD_SETSIZE
-/* Platform can select file descriptors beyond FD_SETSIZE */
-#define IS_SELECTABLE(s) 1
-#elif defined(HAVE_POLL)
+#ifdef HAVE_POLL
 /* Instead of select(), we'll use poll() since poll() works on any fd. */
 #define IS_SELECTABLE(s) 1
 /* Can we call select() with this socket without a buffer overrun? */
 #else
-/* POSIX says selecting file descriptors beyond FD_SETSIZE
-   has undefined behaviour.  If there's no timeout left, we don't have to
-   call select, so it's a safe, little white lie. */
-#define IS_SELECTABLE(s) ((s)->sock_fd < FD_SETSIZE || s->sock_timeout <= 0.0)
+/* If there's no timeout left, we don't have to call select, so it's a safe,
+ * little white lie. */
+#define IS_SELECTABLE(s) (_PyIsSelectable_fd((s)->sock_fd) || (s)->sock_timeout <= 0.0)
 #endif
 
 static PyObject*