[PATCH] xclipboard: avoid overflow crash when building labels

[Kees Cook]

This replaces sprintf with snprintf to avoid crashing when creating
various labels.

https://bugs.launchpad.net/ubuntu/+source/x11-apps/+bug/792642

Signed-off-by: Kees Cook <kees.cook at canonical.com>
---
 xclipboard.c |    3 ++-
 xcutsel.c    |    4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/xclipboard.c b/xclipboard.c
index 1fddf4c..c6610e9 100644
--- a/xclipboard.c
+++ b/xclipboard.c
@@ -334,7 +334,8 @@ AcceptSaveFile(Widget w, XEvent *e, String *argv, Cardinal *argc)
     {
 	char	failMessage[1024];
 
-	sprintf (failMessage, "Can't open file \"%s\"", filename);
+	snprintf (failMessage, sizeof (failMessage),
+                  "Can't open file \"%s\"", filename);
 	XtSetArg (args[0], XtNlabel, failMessage);
 	XtSetValues (failDialog, args, 1);
 	CenterWidgetOnEvent (failDialogShell, e);
diff --git a/xcutsel.c b/xcutsel.c
index 690e201..7f33668 100644
--- a/xcutsel.c
+++ b/xcutsel.c
@@ -288,7 +288,7 @@ main(int argc, char *argv[])
 	XtAddCallback( button, XtNcallback, Quit, NULL );
 
     /* %%% hack alert... */
-    sprintf(label, "*label:copy %s to %d",
+    snprintf(label, sizeof(label), "*label:copy %s to %d",
 	    options.selection_name,
 	    options.buffer);
     XrmPutLineResource( &rdb, label );
@@ -297,7 +297,7 @@ main(int argc, char *argv[])
 	XtCreateManagedWidget("sel-cut", commandWidgetClass, box, NULL, ZERO);
 	XtAddCallback( button, XtNcallback, GetSelection, NULL );
 
-    sprintf(label, "*label:copy %d to %s",
+    snprintf(label, sizeof(label), "*label:copy %d to %s",
 	    options.buffer,
 	    options.selection_name);
     XrmPutLineResource( &rdb, label );
-- 
1.7.4.1


-- 
Kees Cook
Ubuntu Security Team