GH-106008: Fix refleak when peepholing None comparisons (#106367)

brandtbucher · web-flow · commit e4ba71fe4b32 · 2023-07-04T11:03:57.000+01:00
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-07-03-11-38-43.gh-issue-106008.HDf1zd.rst b/Misc/NEWS.d/next/Core and Builtins/2023-07-03-11-38-43.gh-issue-106008.HDf1zd.rst
@@ -0,0 +1,2 @@
+Fix possible reference leaks when failing to optimize comparisons with
+:const:`None` in the bytecode compiler.
diff --git a/Python/flowgraph.c b/Python/flowgraph.c
@@ -1377,9 +1377,9 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
                             goto error;
                         }
                         if (!Py_IsNone(cnt)) {
+                            Py_DECREF(cnt);
                             break;
                         }
-                        Py_DECREF(cnt);
                         if (bb->b_iused <= i + 2) {
                             break;
                         }

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Fix possible reference leaks when failing to optimize comparisons with`
	`2`	+:const:`None` in the bytecode compiler.
Original file line number	Diff line number	Diff line change
`@@ -1377,9 +1377,9 @@ optimize_basic_block(PyObject const_cache, basicblock bb, PyObject *consts)`
`1377`	`1377`	`goto error;`
`1378`	`1378`	`}`
`1379`	`1379`	`if (!Py_IsNone(cnt)) {`
	`1380`	`+ Py_DECREF(cnt);`
`1380`	`1381`	`break;`
`1381`	`1382`	`}`
`1382`		`- Py_DECREF(cnt);`
`1383`	`1383`	`if (bb->b_iused <= i + 2) {`
`1384`	`1384`	`break;`
`1385`	`1385`	`}`