libxl: fix use-after-free in discard_events iteration

We need to use the foreach variant which gets the next pointer before
the loop body is executed.

Coverity-ID: 1056193
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 7a7aaf90fe97acd24a4428a3077c21b7b3398fb1..0879f2331f39cb2dcdbf5a63686c08db87e69572 100644 (file)
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -122,8 +122,8 @@ static void free_disable_deaths(libxl__gc *gc,
 
 static void discard_events(struct libxl__event_list *l) {
     /* doesn't bother unlinking from the list, so l is corrupt on return */
-    libxl_event *ev;
-    LIBXL_TAILQ_FOREACH(ev, l, link)
+    libxl_event *ev, *next;
+    LIBXL_TAILQ_FOREACH_SAFE(ev, l, link, next)
         libxl_event_free(0, ev);
 }