[3.12] gh-102509: Start initializing ob_digit of _PyLongValue (GH-102510) (#107464)

miss-islington · illia-v · web-flow · commit 8f080a290bd4 · 2023-07-31T14:27:59.000+02:00
gh-102509: Start initializing `ob_digit` of `_PyLongValue` (GH-102510) (cherry picked from commit fc130c4) Co-authored-by: Illia Volochii <illia.volochii@gmail.com>
diff --git a/Misc/NEWS.d/next/Security/2023-03-07-21-46-29.gh-issue-102509.5ouaH_.rst b/Misc/NEWS.d/next/Security/2023-03-07-21-46-29.gh-issue-102509.5ouaH_.rst
@@ -0,0 +1,2 @@
+Start initializing ``ob_digit`` during creation of :c:type:`PyLongObject`
+objects. Patch by Illia Volochii.
diff --git a/Objects/longobject.c b/Objects/longobject.c
@@ -163,6 +163,9 @@ _PyLong_New(Py_ssize_t size)
     }
     _PyLong_SetSignAndDigitCount(result, size != 0, size);
     _PyObject_Init((PyObject*)result, &PyLong_Type);
+    /* The digit has to be initialized explicitly to avoid
+     * use-of-uninitialized-value. */
+    result->long_value.ob_digit[0] = 0;
     return result;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+Start initializing ``ob_digit`` during creation of :c:type:`PyLongObject`
	`2`	`+objects. Patch by Illia Volochii.`
Original file line number	Diff line number	Diff line change
`@@ -163,6 +163,9 @@ _PyLong_New(Py_ssize_t size)`
`163`	`163`	`}`
`164`	`164`	`_PyLong_SetSignAndDigitCount(result, size != 0, size);`
`165`	`165`	`_PyObject_Init((PyObject*)result, &PyLong_Type);`
	`166`	`+ /* The digit has to be initialized explicitly to avoid`
	`167`	`+ * use-of-uninitialized-value. */`
	`168`	`+ result->long_value.ob_digit[0] = 0;`
`166`	`169`	`return result;`
`167`	`170`	`}`
`168`	`171`