[media] v4l2-event: Remove pending events from fh event queue when unsubscribing

The kev pointers inside the pending events queue (the available queue) of the
fh point to data inside the sev, unsubscribing frees the sev, thus making these
pointers point to freed memory!

This patch fixes these dangling pointers in the available queue by removing
all matching pending events on unsubscription.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index 9f56f18d509fe82fd2728da1b824ca2c3f797216..4d01f17497f6b710270c05cc850660fc8f07fe2f 100644 (file)
--- a/drivers/media/video/v4l2-event.c
+++ b/drivers/media/video/v4l2-event.c
@@ -285,6 +285,7 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 {
        struct v4l2_subscribed_event *sev;
        unsigned long flags;
+       int i;
 
        if (sub->type == V4L2_EVENT_ALL) {
                v4l2_event_unsubscribe_all(fh);
@@ -295,6 +296,11 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 
        sev = v4l2_event_subscribed(fh, sub->type, sub->id);
        if (sev != NULL) {
+               /* Remove any pending events for this subscription */
+               for (i = 0; i < sev->in_use; i++) {
+                       list_del(&sev->events[sev_pos(sev, i)].list);
+                       fh->navailable--;
+               }
                list_del(&sev->list);
                sev->fh = NULL;
        }