commit 82a907560011c7b784badccc78082cef70ea7128
author Serhiy Storchaka <storchaka@gmail.com> Tue Jul 11 07:27:56 2017 +0300
committer GitHub <noreply@github.com> Tue Jul 11 07:27:56 2017 +0300
tree 54b1e14dd770cea0090d1b03fa9daa67fa51af65
parent ecfe4f678bfb0e3c19c90fd7db79c5f3c76023e4

[3.6] bpo-22207: Add checks for possible integer overflows in unicodeobject.c. (GH-2623) (#2658)

Based on patch by Victor Stinner.
(cherry picked from commit 64e461b)

Objects/unicodeobject.c

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 494cdbd..1650370 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -5513,13 +5513,12 @@
         /* four bytes are reserved for each surrogate */
         if (moreunits > 1) {
             Py_ssize_t outpos = out - (uint32_t*) PyBytes_AS_STRING(v);
-            Py_ssize_t morebytes = 4 * (moreunits - 1);
-            if (PyBytes_GET_SIZE(v) > PY_SSIZE_T_MAX - morebytes) {
+            if (moreunits >= (PY_SSIZE_T_MAX - PyBytes_GET_SIZE(v)) / 4) {
                 /* integer overflow */
                 PyErr_NoMemory();
                 goto error;
             }
-            if (_PyBytes_Resize(&v, PyBytes_GET_SIZE(v) + morebytes) < 0)
+            if (_PyBytes_Resize(&v, PyBytes_GET_SIZE(v) + 4 * (moreunits - 1)) < 0)
                 goto error;
             out = (uint32_t*) PyBytes_AS_STRING(v) + outpos;
         }
@@ -5865,13 +5864,12 @@
         /* two bytes are reserved for each surrogate */
         if (moreunits > 1) {
             Py_ssize_t outpos = out - (unsigned short*) PyBytes_AS_STRING(v);
-            Py_ssize_t morebytes = 2 * (moreunits - 1);
-            if (PyBytes_GET_SIZE(v) > PY_SSIZE_T_MAX - morebytes) {
+            if (moreunits >= (PY_SSIZE_T_MAX - PyBytes_GET_SIZE(v)) / 2) {
                 /* integer overflow */
                 PyErr_NoMemory();
                 goto error;
             }
-            if (_PyBytes_Resize(&v, PyBytes_GET_SIZE(v) + morebytes) < 0)
+            if (_PyBytes_Resize(&v, PyBytes_GET_SIZE(v) + 2 * (moreunits - 1)) < 0)
                 goto error;
             out = (unsigned short*) PyBytes_AS_STRING(v) + outpos;
         }
@@ -6551,6 +6549,10 @@
                      1))
         return NULL;
 
+    if (size < 0) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
     if (size == 0)
         _Py_RETURN_UNICODE_EMPTY();
 
@@ -7352,6 +7354,10 @@
         PyErr_SetString(PyExc_ValueError, "invalid code page number");
         return NULL;
     }
+    if (size < 0) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
 
     if (consumed)
         *consumed = 0;