From e92381a0a6a3e1f000956e1f1e70e543b9c2bcd5 Mon Sep 17 00:00:00 2001

From: Benjamin Peterson <benjamin@python.org>

Date: Mon, 18 Jan 2021 14:47:05 -0600

Subject: [PATCH] [3.6] closes bpo-42938: Replace snprintf with Python unicode

 formatting in ctypes param reprs. (24239). (cherry picked from commit

 916610ef90a0d0761f08747f7b0905541f0977c7)

Co-authored-by: Benjamin Peterson <benjamin@python.org>

---

 Lib/ctypes/test/test_parameters.py            | 43 +++++++++++++++

 .../2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst  |  2 +

 Modules/_ctypes/callproc.c                    | 55 +++++++------------

 3 files changed, 66 insertions(+), 34 deletions(-)

 create mode 100644 Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst

diff --git a/Lib/ctypes/test/test_parameters.py b/Lib/ctypes/test/test_parameters.py

index e4c25fd880cef..531894fdec838 100644

--- a/Lib/ctypes/test/test_parameters.py

+++ b/Lib/ctypes/test/test_parameters.py

@@ -201,6 +201,49 @@ def __dict__(self):

         with self.assertRaises(ZeroDivisionError):

             WorseStruct().__setstate__({}, b'foo')

+    def test_parameter_repr(self):

+        from ctypes import (

+            c_bool,

+            c_char,

+            c_wchar,

+            c_byte,

+            c_ubyte,

+            c_short,

+            c_ushort,

+            c_int,

+            c_uint,

+            c_long,

+            c_ulong,

+            c_longlong,

+            c_ulonglong,

+            c_float,

+            c_double,

+            c_longdouble,

+            c_char_p,

+            c_wchar_p,

+            c_void_p,

+        )

+        self.assertRegex(repr(c_bool.from_param(True)), r"^<cparam '\?' at 0x[A-Fa-f0-9]+>$")

+        self.assertEqual(repr(c_char.from_param(97)), "<cparam 'c' ('a')>")

+        self.assertRegex(repr(c_wchar.from_param('a')), r"^<cparam 'u' at 0x[A-Fa-f0-9]+>$")

+        self.assertEqual(repr(c_byte.from_param(98)), "<cparam 'b' (98)>")

+        self.assertEqual(repr(c_ubyte.from_param(98)), "<cparam 'B' (98)>")

+        self.assertEqual(repr(c_short.from_param(511)), "<cparam 'h' (511)>")

+        self.assertEqual(repr(c_ushort.from_param(511)), "<cparam 'H' (511)>")

+        self.assertRegex(repr(c_int.from_param(20000)), r"^<cparam '[li]' \(20000\)>$")

+        self.assertRegex(repr(c_uint.from_param(20000)), r"^<cparam '[LI]' \(20000\)>$")

+        self.assertRegex(repr(c_long.from_param(20000)), r"^<cparam '[li]' \(20000\)>$")

+        self.assertRegex(repr(c_ulong.from_param(20000)), r"^<cparam '[LI]' \(20000\)>$")

+        self.assertRegex(repr(c_longlong.from_param(20000)), r"^<cparam '[liq]' \(20000\)>$")

+        self.assertRegex(repr(c_ulonglong.from_param(20000)), r"^<cparam '[LIQ]' \(20000\)>$")

+        self.assertEqual(repr(c_float.from_param(1.5)), "<cparam 'f' (1.5)>")

+        self.assertEqual(repr(c_double.from_param(1.5)), "<cparam 'd' (1.5)>")

+        self.assertEqual(repr(c_double.from_param(1e300)), "<cparam 'd' (1e+300)>")

+        self.assertRegex(repr(c_longdouble.from_param(1.5)), r"^<cparam ('d' \(1.5\)|'g' at 0x[A-Fa-f0-9]+)>$")

+        self.assertRegex(repr(c_char_p.from_param(b'hihi')), "^<cparam 'z' \(0x[A-Fa-f0-9]+\)>$")

+        self.assertRegex(repr(c_wchar_p.from_param('hihi')), "^<cparam 'Z' \(0x[A-Fa-f0-9]+\)>$")

+        self.assertRegex(repr(c_void_p.from_param(0x12)), r"^<cparam 'P' \(0x0*12\)>$")

+

 ################################################################

 if __name__ == '__main__':

diff --git a/Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst b/Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst

new file mode 100644

index 0000000000000..7df65a156feab

--- /dev/null

+++ b/Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst

@@ -0,0 +1,2 @@

+Avoid static buffers when computing the repr of :class:`ctypes.c_double` and

+:class:`ctypes.c_longdouble` values.

diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c

index d1c190f359108..2bb289bce043f 100644

--- a/Modules/_ctypes/callproc.c

+++ b/Modules/_ctypes/callproc.c

@@ -461,58 +461,47 @@ is_literal_char(unsigned char c)

 static PyObject *

 PyCArg_repr(PyCArgObject *self)

 {

-    char buffer[256];

     switch(self->tag) {

     case 'b':

     case 'B':

-        sprintf(buffer, "<cparam '%c' (%d)>",

+        return PyUnicode_FromFormat("<cparam '%c' (%d)>",

             self->tag, self->value.b);

-        break;

     case 'h':

     case 'H':

-        sprintf(buffer, "<cparam '%c' (%d)>",

+        return PyUnicode_FromFormat("<cparam '%c' (%d)>",

             self->tag, self->value.h);

-        break;

     case 'i':

     case 'I':

-        sprintf(buffer, "<cparam '%c' (%d)>",

+        return PyUnicode_FromFormat("<cparam '%c' (%d)>",

             self->tag, self->value.i);

-        break;

     case 'l':

     case 'L':

-        sprintf(buffer, "<cparam '%c' (%ld)>",

+        return PyUnicode_FromFormat("<cparam '%c' (%ld)>",

             self->tag, self->value.l);

-        break;

     case 'q':

     case 'Q':

-        sprintf(buffer,

-#ifdef MS_WIN32

-            "<cparam '%c' (%I64d)>",

-#else

-            "<cparam '%c' (%lld)>",

-#endif

+        return PyUnicode_FromFormat("<cparam '%c' (%lld)>",

             self->tag, self->value.q);

-        break;

     case 'd':

-        sprintf(buffer, "<cparam '%c' (%f)>",

-            self->tag, self->value.d);

-        break;

-    case 'f':

-        sprintf(buffer, "<cparam '%c' (%f)>",

-            self->tag, self->value.f);

-        break;

-

+    case 'f': {

+        PyObject *f = PyFloat_FromDouble((self->tag == 'f') ? self->value.f : self->value.d);

+        if (f == NULL) {

+            return NULL;

+        }

+        PyObject *result = PyUnicode_FromFormat("<cparam '%c' (%R)>", self->tag, f);

+        Py_DECREF(f);

+        return result;

+    }

     case 'c':

         if (is_literal_char((unsigned char)self->value.c)) {

-            sprintf(buffer, "<cparam '%c' ('%c')>",

+            return PyUnicode_FromFormat("<cparam '%c' ('%c')>",

                 self->tag, self->value.c);

         }

         else {

-            sprintf(buffer, "<cparam '%c' ('\\x%02x')>",

+            return PyUnicode_FromFormat("<cparam '%c' ('\\x%02x')>",

                 self->tag, (unsigned char)self->value.c);

         }

-        break;

 /* Hm, are these 'z' and 'Z' codes useful at all?

    Shouldn't they be replaced by the functionality of c_string

@@ -521,22 +510,20 @@ PyCArg_repr(PyCArgObject *self)

     case 'z':

     case 'Z':

     case 'P':

-        sprintf(buffer, "<cparam '%c' (%p)>",

+        return PyUnicode_FromFormat("<cparam '%c' (%p)>",

             self->tag, self->value.p);

         break;

     default:

         if (is_literal_char((unsigned char)self->tag)) {

-            sprintf(buffer, "<cparam '%c' at %p>",

-                (unsigned char)self->tag, self);

+            return PyUnicode_FromFormat("<cparam '%c' at %p>",

+                (unsigned char)self->tag, (void *)self);

         }

         else {

-            sprintf(buffer, "<cparam 0x%02x at %p>",

-                (unsigned char)self->tag, self);

+            return PyUnicode_FromFormat("<cparam 0x%02x at %p>",

+                (unsigned char)self->tag, (void *)self);

         }

-        break;

     }

-    return PyUnicode_FromString(buffer);

 }

 static PyMemberDef PyCArgType_members[] = {