bpo-34879: Fix a possible null pointer dereference in bytesobject.c (GH-9683)

miss-islington · ZackerySpytz · web-flow · commit 6580e52b64cb · 2018-10-02T23:34:05.000-07:00
formatfloat() was not checking if PyBytes_FromStringAndSize() failed, which could lead to a null pointer dereference in _PyBytes_FormatEx(). (cherry picked from commit 96c5932) Co-authored-by: Zackery Spytz <zspytz@gmail.com>
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-10-02-22-55-11.bpo-34879.7VNH2a.rst b/Misc/NEWS.d/next/Core and Builtins/2018-10-02-22-55-11.bpo-34879.7VNH2a.rst
@@ -0,0 +1,2 @@
+Fix a possible null pointer dereference in bytesobject.c.  Patch by Zackery
+Spytz.
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
@@ -446,7 +446,7 @@ formatfloat(PyObject *v, int flags, int prec, int type,
     result = PyBytes_FromStringAndSize(p, len);
     PyMem_Free(p);
     *p_result = result;
-    return str;
+    return result != NULL ? str : NULL;
 }
 
 static PyObject *

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Fix a possible null pointer dereference in bytesobject.c. Patch by Zackery`
	`2`	`+Spytz.`
Original file line number	Diff line number	Diff line change
`@@ -446,7 +446,7 @@ formatfloat(PyObject *v, int flags, int prec, int type,`
`446`	`446`	`result = PyBytes_FromStringAndSize(p, len);`
`447`	`447`	`PyMem_Free(p);`
`448`	`448`	`*p_result = result;`
`449`		`- return str;`
	`449`	`+ return result != NULL ? str : NULL;`
`450`	`450`	`}`
`451`	`451`
`452`	`452`	`static PyObject *`