bpo-30961: Fix decrementing a borrowed reference in tracemalloc. (#2747) (#2748)

zhangyangyu · web-flow · commit 241c4a28d9fe · 2017-07-19T00:50:52.000+08:00
(cherry picked from commit 4ed5ad7)
diff --git a/Misc/NEWS.d/next/Library/2017-07-18-23-47-51.bpo-30961.064jz0.rst b/Misc/NEWS.d/next/Library/2017-07-18-23-47-51.bpo-30961.064jz0.rst
@@ -0,0 +1 @@
+Fix decrementing a borrowed reference in tracemalloc.
diff --git a/Modules/_tracemalloc.c b/Modules/_tracemalloc.c
@@ -1731,7 +1731,7 @@ _PyTraceMalloc_Init(void)
         if (key == NULL)
             return -1;
 
-        value = PyDict_GetItemWithError(xoptions, key);
+        value = PyDict_GetItemWithError(xoptions, key); /* borrowed */
         Py_DECREF(key);
         if (value == NULL) {
             if (PyErr_Occurred())
@@ -1742,7 +1742,6 @@ _PyTraceMalloc_Init(void)
         }
 
         nframe = parse_sys_xoptions(value);
-        Py_DECREF(value);
         if (nframe < 0) {
             Py_FatalError("-X tracemalloc=NFRAME: invalid number of frames");
         }

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+Fix decrementing a borrowed reference in tracemalloc.`
Original file line number	Diff line number	Diff line change
`@@ -1731,7 +1731,7 @@ _PyTraceMalloc_Init(void)`
`1731`	`1731`	`if (key == NULL)`
`1732`	`1732`	`return -1;`
`1733`	`1733`
`1734`		`- value = PyDict_GetItemWithError(xoptions, key);`
	`1734`	`+ value = PyDict_GetItemWithError(xoptions, key); /* borrowed */`
`1735`	`1735`	`Py_DECREF(key);`
`1736`	`1736`	`if (value == NULL) {`
`1737`	`1737`	`if (PyErr_Occurred())`
`@@ -1742,7 +1742,6 @@ _PyTraceMalloc_Init(void)`
`1742`	`1742`	`}`
`1743`	`1743`
`1744`	`1744`	`nframe = parse_sys_xoptions(value);`
`1745`		`- Py_DECREF(value);`
`1746`	`1745`	`if (nframe < 0) {`
`1747`	`1746`	`Py_FatalError("-X tracemalloc=NFRAME: invalid number of frames");`
`1748`	`1747`	`}`