GH-96187: Prevent _PyCode_GetExtra to return garbage for negative indexes (GH-96188)

(cherry picked from commit 16ebae4cd4029205d932751f26c719c6cb8a6e92)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>

diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-08-22-21-33-28.gh-issue-96187.W_6SRG.rst b/Misc/NEWS.d/next/Core and Builtins/2022-08-22-21-33-28.gh-issue-96187.W_6SRG.rst
new file mode 100644 (file)
index 0000000..fd194fa
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-08-22-21-33-28.gh-issue-96187.W_6SRG.rst
@@ -0,0 +1,2 @@
+Fixed a bug that caused ``_PyCode_GetExtra`` to return garbage for negative
+indexes. Patch by Pablo Galindo

diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index c0151434489ad1750ac2f1e4f2666d02fe5596c7..d7434ddefbc02670660165c0f1a116e9af37d265 100644 (file)
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -1337,7 +1337,7 @@ _PyCode_GetExtra(PyObject *code, Py_ssize_t index, void **extra)
     PyCodeObject *o = (PyCodeObject*) code;
     _PyCodeObjectExtra *co_extra = (_PyCodeObjectExtra*) o->co_extra;
 
-    if (co_extra == NULL || co_extra->ce_size <= index) {
+    if (co_extra == NULL || index < 0 || co_extra->ce_size <= index) {
         *extra = NULL;
         return 0;
     }