From: Erlend E. Aasland <erlend.aasland@protonmail.com>
Date: Tue, 13 Jun 2023 09:07:20 +0000 (+0200)
Subject: [3.11] gh-105375: Improve error handling in _Unpickler_SetInputStream() (#105667... 
X-Git-Tag: v3.11.5~279
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2b1745f37ca086c24fce7a196dfd3e2d57238cc8;p=thirdparty%2FPython%2Fcpython.git

[3.11] gh-105375: Improve error handling in _Unpickler_SetInputStream() (#105667) (#105721)

Prevent exceptions from possibly being overwritten in case of multiple
failures.

(cherry picked from commit 217589d4f3246d67c6ef0eb0be2b1c33987cf260)
---

diff --git a/Misc/NEWS.d/next/Library/2023-06-11-22-46-06.gh-issue-105375.YkhSNt.rst b/Misc/NEWS.d/next/Library/2023-06-11-22-46-06.gh-issue-105375.YkhSNt.rst
new file mode 100644
index 000000000000..dda8f428760b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-06-11-22-46-06.gh-issue-105375.YkhSNt.rst
@@ -0,0 +1,2 @@
+Fix a bug in :c:func:`!_Unpickler_SetInputStream` where an exception could
+end up being overwritten in case of failure.
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 08bdb4936f88..840877e2db64 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -1666,25 +1666,30 @@ _Unpickler_SetInputStream(UnpicklerObject *self, PyObject *file)
 {
     /* Optional file methods */
     if (_PyObject_LookupAttr(file, &_Py_ID(peek), &self->peek) < 0) {
-        return -1;
+        goto error;
     }
     if (_PyObject_LookupAttr(file, &_Py_ID(readinto), &self->readinto) < 0) {
-        return -1;
+        goto error;
+    }
+    if (_PyObject_LookupAttr(file, &_Py_ID(read), &self->read) < 0) {
+        goto error;
+    }
+    if (_PyObject_LookupAttr(file, &_Py_ID(readline), &self->readline) < 0) {
+        goto error;
     }
-    (void)_PyObject_LookupAttr(file, &_Py_ID(read), &self->read);
-    (void)_PyObject_LookupAttr(file, &_Py_ID(readline), &self->readline);
     if (!self->readline || !self->read) {
-        if (!PyErr_Occurred()) {
-            PyErr_SetString(PyExc_TypeError,
-                            "file must have 'read' and 'readline' attributes");
-        }
-        Py_CLEAR(self->read);
-        Py_CLEAR(self->readinto);
-        Py_CLEAR(self->readline);
-        Py_CLEAR(self->peek);
-        return -1;
+        PyErr_SetString(PyExc_TypeError,
+                        "file must have 'read' and 'readline' attributes");
+        goto error;
     }
     return 0;
+
+error:
+    Py_CLEAR(self->read);
+    Py_CLEAR(self->readinto);
+    Py_CLEAR(self->readline);
+    Py_CLEAR(self->peek);
+    return -1;
 }
 
 /* Returns -1 (with an exception set) on failure, 0 on success. This may