[3.11] gh-116447: Fix possible UB in arraymodule and getargs (GH-116459) (#116497)

miss-islington · sobolevn · web-flow · commit 3abf26778782 · 2024-03-08T11:25:39.000Z
gh-116447: Fix possible UB in `arraymodule` and `getargs` (GH-116459) (cherry picked from commit fdb2d90) Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
@@ -244,7 +244,7 @@ BB_setitem(arrayobject *ap, Py_ssize_t i, PyObject *v)
     if (!PyArg_Parse(v, "b;array item must be integer", &x))
         return -1;
     if (i >= 0)
-        ((char *)ap->ob_item)[i] = x;
+        ((unsigned char *)ap->ob_item)[i] = x;
     return 0;
 }
 
diff --git a/Python/getargs.c b/Python/getargs.c
@@ -672,7 +672,7 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
     switch (c) {
 
     case 'b': { /* unsigned byte -- very short int */
-        char *p = va_arg(*p_va, char *);
+        unsigned char *p = va_arg(*p_va, unsigned char *);
         long ival = PyLong_AsLong(arg);
         if (ival == -1 && PyErr_Occurred())
             RETURN_ERR_OCCURRED;
@@ -693,7 +693,7 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
 
     case 'B': {/* byte sized bitfield - both signed and unsigned
                   values allowed */
-        char *p = va_arg(*p_va, char *);
+        unsigned char *p = va_arg(*p_va, unsigned char *);
         unsigned long ival = PyLong_AsUnsignedLongMask(arg);
         if (ival == (unsigned long)-1 && PyErr_Occurred())
             RETURN_ERR_OCCURRED;

Original file line number	Diff line number	Diff line change
`@@ -244,7 +244,7 @@ BB_setitem(arrayobject ap, Py_ssize_t i, PyObject v)`
`244`	`244`	`if (!PyArg_Parse(v, "b;array item must be integer", &x))`
`245`	`245`	`return -1;`
`246`	`246`	`if (i >= 0)`
`247`		`- ((char *)ap->ob_item)[i] = x;`
	`247`	`+ ((unsigned char *)ap->ob_item)[i] = x;`
`248`	`248`	`return 0;`
`249`	`249`	`}`
`250`	`250`