Armin's patch to prevent overflows.
diff --git a/Modules/collectionsmodule.c b/Modules/collectionsmodule.c
index 15530a7..a766eec 100644
--- a/Modules/collectionsmodule.c
+++ b/Modules/collectionsmodule.c
@@ -52,8 +52,21 @@
} block;
static block *
-newblock(block *leftlink, block *rightlink) {
- block *b = PyMem_Malloc(sizeof(block));
+newblock(block *leftlink, block *rightlink, int len) {
+ block *b;
+ /* To prevent len from overflowing INT_MAX on 64-bit machines, we
+ * refuse to allocate new blocks if the current len is dangerously
+ * close. There is some extra margin to prevent spurious arithmetic
+ * overflows at various places. The following check ensures that
+ * the blocks allocated to the deque, in the worst case, can only
+ * have INT_MAX-2 entries in total.
+ */
+ if (len >= INT_MAX - 2*BLOCKLEN) {
+ PyErr_SetString(PyExc_OverflowError,
+ "cannot add more blocks to the deque");
+ return NULL;
+ }
+ b = PyMem_Malloc(sizeof(block));
if (b == NULL) {
PyErr_NoMemory();
return NULL;
@@ -87,7 +100,7 @@
if (deque == NULL)
return NULL;
- b = newblock(NULL, NULL);
+ b = newblock(NULL, NULL, 0);
if (b == NULL) {
Py_DECREF(deque);
return NULL;
@@ -110,7 +123,7 @@
{
deque->state++;
if (deque->rightindex == BLOCKLEN-1) {
- block *b = newblock(deque->rightblock, NULL);
+ block *b = newblock(deque->rightblock, NULL, deque->len);
if (b == NULL)
return NULL;
assert(deque->rightblock->rightlink == NULL);
@@ -132,7 +145,7 @@
{
deque->state++;
if (deque->leftindex == 0) {
- block *b = newblock(NULL, deque->leftblock);
+ block *b = newblock(NULL, deque->leftblock, deque->len);
if (b == NULL)
return NULL;
assert(deque->leftblock->leftlink == NULL);
@@ -235,7 +248,8 @@
while ((item = PyIter_Next(it)) != NULL) {
deque->state++;
if (deque->rightindex == BLOCKLEN-1) {
- block *b = newblock(deque->rightblock, NULL);
+ block *b = newblock(deque->rightblock, NULL,
+ deque->len);
if (b == NULL) {
Py_DECREF(item);
Py_DECREF(it);
@@ -271,7 +285,8 @@
while ((item = PyIter_Next(it)) != NULL) {
deque->state++;
if (deque->leftindex == 0) {
- block *b = newblock(NULL, deque->leftblock);
+ block *b = newblock(NULL, deque->leftblock,
+ deque->len);
if (b == NULL) {
Py_DECREF(item);
Py_DECREF(it);