[Python-checkins] bpo-34770: Fix a possible null pointer dereference in pyshellext.cpp (GH-9497)

Tue Sep 25 00:25:28 EDT 2018

https://github.com/python/cpython/commit/f6c8007a29b95b3ea3ca687a9b4924769a696328
commit: f6c8007a29b95b3ea3ca687a9b4924769a696328
branch: master
author: Zackery Spytz <zspytz at gmail.com>
committer: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
date: 2018年09月24日T21:25:23-07:00
summary:
bpo-34770: Fix a possible null pointer dereference in pyshellext.cpp (GH-9497)
The GlobalLock() call in UpdateDropDescription() was not checked for
failure.
https://bugs.python.org/issue34770
files:
A Misc/NEWS.d/next/Windows/2018-09-22-11-02-35.bpo-34770.4lEUOd.rst
M PC/pyshellext.cpp

diff --git a/Misc/NEWS.d/next/Windows/2018-09-22-11-02-35.bpo-34770.4lEUOd.rst b/Misc/NEWS.d/next/Windows/2018-09-22-11-02-35.bpo-34770.4lEUOd.rst
new file mode 100644
index 000000000000..5e4ba8868e84
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2018-09-22-11-02-35.bpo-34770.4lEUOd.rst
@@ -0,0 +1 @@
+Fix a possible null pointer dereference in pyshellext.cpp.
diff --git a/PC/pyshellext.cpp b/PC/pyshellext.cpp
index 04fe61e89618..019880264bee 100644
--- a/PC/pyshellext.cpp
+++ b/PC/pyshellext.cpp
@@ -172,6 +172,11 @@ class PyShellExt : public RuntimeClass<
 return E_FAIL;
 }
 auto dd = (DROPDESCRIPTION*)GlobalLock(medium.hGlobal);
+ if (!dd) {
+ OutputDebugString(L"PyShellExt::UpdateDropDescription - failed to lock DROPDESCRIPTION hGlobal");
+ ReleaseStgMedium(&medium);
+ return E_FAIL;
+ }
 StringCchCopy(dd->szMessage, sizeof(dd->szMessage) / sizeof(dd->szMessage[0]), DRAG_MESSAGE);
 StringCchCopy(dd->szInsert, sizeof(dd->szInsert) / sizeof(dd->szInsert[0]), PathFindFileNameW(target));
 dd->type = DROPIMAGE_MOVE;
