Quserex.dll load security

5 files changed, 26 insertions, 10 deletions

diff --git a/ChangeLog b/ChangeLog
index 04a81c9..2b1ba40 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
 	* pthread_spin_unlock.c (EPERM): Return success if unlocking a lock

 	that is not locked, because single CPU machines wrap a

 	PTHREAD_MUTEX_NORMAL mutex, which returns success in this case.

+	* pthread_win32_attach_detach_np.c (QUSEREX.DLL): Load from an

+	absolute path only which must be the Windows System folder.

 

 2011-07-03 Daniel Richard G. <skunk at iskunk dot org>

 

diff --git a/NEWS b/NEWS
index f39c587..219fe4e 100644
--- a/NEWS
+++ b/NEWS
@@ -117,6 +117,10 @@ MCS queue-based locks to reduce resource consumption, in particular use of Win32
 objects.
 - Ross Johnson
 
+For security, the QuserEx.dll if used must now be installed in the Windows System
+folder.
+- Ross Johnson
+
 New tests
 ---------
 robust[1-5].c - Robust mutexes
diff --git a/README b/README
index 553ec71..545360b 100644
--- a/README
+++ b/README
@@ -51,9 +51,9 @@ QueueUserAPCEx by Panagiotis E. Hadjidoukas
 	are runnable. The simulated async cancellation cannot cancel blocked
 	threads.
 
-	QueueUserAPCEx is required in C++ builds to avoid longjmp-style
-	context switching in pthread_cancel(), which will otherwise affect
-	exception handling and proper application behaviour.
+        [FOR SECURITY] To be found Quserex.dll MUST be installed in the
+	Windows System Folder. This is not an unreasonable constraint given a
+	driver must also be installed and loaded at system startup.
 
 
 Library naming
@@ -87,8 +87,8 @@ can differentiate between binary incompatible versions of the
 libs and dlls.
 
 In general:
-	pthread[VG]{SE,CE,C}c.dll
-	pthread[VG]{SE,CE,C}c.lib
+	pthread[VG]{SE,CE,C}[c].dll
+	pthread[VG]{SE,CE,C}[c].lib
 
 where:
 	[VG] indicates the compiler
@@ -102,7 +102,7 @@ where:
 
 	c	- DLL compatibility number indicating ABI and API
 		  compatibility with applications built against
-		  any snapshot with the same compatibility number.
+		  a snapshot with the same compatibility number.
 		  See 'Version numbering' below.
 
 The name may also be suffixed by a 'd' to indicate a debugging version
@@ -110,7 +110,7 @@ of the library. E.g. pthreadVC2d.lib. Debugging versions contain
 additional information for debugging (symbols etc) and are often not
 optimised in any way (compiled with optimisation turned off).
 
-For example:
+Examples:
 	pthreadVSE.dll	(MSVC/SEH)
 	pthreadGCE.dll	(GNUC/C++ EH)
 	pthreadGC.dll	(GNUC/not dependent on exceptions)
diff --git a/implement.h b/implement.h
index 937a0cb..6b9f425 100644
--- a/implement.h
+++ b/implement.h
@@ -39,7 +39,7 @@
 #define _IMPLEMENT_H
 
 #if !defined(_WIN32_WINNT)
-#define _WIN32_WINNT 0x400
+#define _WIN32_WINNT 0x0400
 #endif
 
 #include <windows.h>
diff --git a/pthread_win32_attach_detach_np.c b/pthread_win32_attach_detach_np.c
index aa30a65..d26a632 100644
--- a/pthread_win32_attach_detach_np.c
+++ b/pthread_win32_attach_detach_np.c
@@ -45,6 +45,7 @@ static HINSTANCE ptw32_h_quserex;
 BOOL
 pthread_win32_process_attach_np ()
 {
+  TCHAR WindowsSystemDirBuf[1024];
   BOOL result = TRUE;
 
   result = ptw32_processInitialize ();
@@ -60,9 +61,18 @@ pthread_win32_process_attach_np ()
 #endif
 
   /*
-   * Load QUSEREX.DLL and try to get address of QueueUserAPCEx
+   * Load QUSEREX.DLL and try to get address of QueueUserAPCEx.
+   * Because QUSEREX.DLL requires a driver to be installed we will
+   * assume the DLL is in the system directory.
+   *
+   * This should take care of any security issues.
    */
-  ptw32_h_quserex = LoadLibrary (TEXT ("QUSEREX.DLL"));
+  if(GetSystemDirectory(WindowsSystemDirBuf, sizeof(WindowsSystemDirBuf)))
+  {
+    ptw32_h_quserex = LoadLibrary (TEXT (strncat(WindowsSystemDirBuf,
+                                                 "\\QUSEREX.DLL",
+                                                 sizeof(WindowsSystemDirBuf))));
+  }
 
   if (ptw32_h_quserex != NULL)
     {