Issue #16096: Fix several occurrences of potential signed integer overflow. Thanks Serhiy Storchaka.

1 files changed, 3 insertions, 4 deletions

diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 01c85d1cd3..873d46fd1b 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -1265,14 +1265,13 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
         assert(ptoappend != NULL);
         assert(ntoappend > 0);
         while (usednew + ntoappend > totalnew) {
-            size_t bigger = totalnew << 1;
-            if ((bigger >> 1) != totalnew) { /* overflow */
+            if (totalnew > (PY_SSIZE_T_MAX >> 1)) { /* overflow */
                 PyErr_NoMemory();
                 goto Done;
             }
-            if (_PyBytes_Resize(&newfmt, bigger) < 0)
+            totalnew <<= 1;
+            if (_PyBytes_Resize(&newfmt, totalnew) < 0)
                 goto Done;
-            totalnew = bigger;
             pnew = PyBytes_AsString(newfmt) + usednew;
         }
         memcpy(pnew, ptoappend, ntoappend);