mini-os: fix use-after-free in xs_daemon_close event iteration

We need to get the next pointer before the freeing of the event.

Coverity-ID: 1056173
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Acked-By: Samuel Thibault <samuel.thibault@ens-lyon.org>

diff --git a/lib/xs.c b/lib/xs.c
index a2a122098cce7d42647c328283af021787f83f27..c603d178bf53f4740c7ca4d0dbccbce27eec3786 100644 (file)
--- a/lib/xs.c
+++ b/lib/xs.c
@@ -29,9 +29,12 @@ struct xs_handle *xs_daemon_open()
 void xs_daemon_close(struct xs_handle *h)
 {
     int fd = _xs_fileno(h);
-    struct xenbus_event *event;
-    for (event = files[fd].xenbus.events; event; event = event->next)
+    struct xenbus_event *event, *next;
+    for (event = files[fd].xenbus.events; event; event = next)
+    {
+        next = event->next;
         free(event);
+    }
     files[fd].type = FTYPE_NONE;
 }