diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 1b2562bfa..7c2f442e5 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2013-06-17  Corinna Vinschen  <corinna@vinschen.de>
+
+	* fhandler_clipboard.cc (fhandler_dev_clipboard::read): Fix buffer
+	read access overrun when pos > 0.
+
 2013-06-17  Corinna Vinschen  <corinna@vinschen.de>
 
 	* times.cc (GetSystemTimePreciseAsFileTime): Add comment to declaration.
diff --git a/winsup/cygwin/fhandler_clipboard.cc b/winsup/cygwin/fhandler_clipboard.cc
index 1118137c1..db72b9787 100644
--- a/winsup/cygwin/fhandler_clipboard.cc
+++ b/winsup/cygwin/fhandler_clipboard.cc
@@ -295,7 +295,8 @@ fhandler_dev_clipboard::read (void *ptr, size_t& len)
 		  != (size_t) -1
 		 && (ret > conv_len
 			/* Skip separated high surrogate: */
-		     || ((buf [pos + glen - 1] & 0xFC00) == 0xD800 && glen - pos > 1)))
+		     || ((buf [glen - 1] & 0xFC00) == 0xD800
+			 && glen - pos > 1)))
 	     --glen;
 	  if (ret == (size_t) -1)
 	    ret = 0;
diff --git a/winsup/cygwin/release/1.7.21 b/winsup/cygwin/release/1.7.21
index 0eb3de3a4..2ea267778 100644
--- a/winsup/cygwin/release/1.7.21
+++ b/winsup/cygwin/release/1.7.21
@@ -8,3 +8,6 @@ Bug fixes:
 - Fix long-standing problem which allows to access files via ".." using an
   invalid POSIX path, for instance, `cd nonexistant/../existing_dir".
   Fixes: http://cygwin.com/ml/cygwin/2013-05/msg00222.html
+
+- Fix EFAULT when reading large clipboard.
+  Fixes: http://cygwin.com/ml/cygwin/2013-06/msg00311.html