Issue #14716: Change integer overflow check in unicode_writer_prepare()
to compute the limit at compile time instead of runtime. Patch writen by Serhiy
Storchaka.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 0722312..4bbaa35 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -13242,8 +13242,10 @@
newlen = writer->pos + length;
if (newlen > PyUnicode_GET_LENGTH(writer->buffer)) {
- /* overallocate 25% to limit the number of resize */
- if (newlen <= (PY_SSIZE_T_MAX - newlen / 4))
+ /* Overallocate 25% to limit the number of resize.
+ Check for integer overflow:
+ (newlen + newlen / 4) <= PY_SSIZE_T_MAX */
+ if (newlen <= (PY_SSIZE_T_MAX - PY_SSIZE_T_MAX / 5))
newlen += newlen / 4;
if (maxchar > writer->maxchar) {