4.4-stable patches

added patches:
	media-v4l-event-prevent-freeing-event-subscriptions-while-accessed.patch

diff --git a/queue-4.4/media-v4l-event-prevent-freeing-event-subscriptions-while-accessed.patch b/queue-4.4/media-v4l-event-prevent-freeing-event-subscriptions-while-accessed.patch
new file mode 100644 (file)
index 0000000..e8b41b8
--- /dev/null
+++ b/queue-4.4/media-v4l-event-prevent-freeing-event-subscriptions-while-accessed.patch
@@ -0,0 +1,154 @@
+From ad608fbcf166fec809e402d548761768f602702c Mon Sep 17 00:00:00 2001
+From: Sakari Ailus <sakari.ailus@linux.intel.com>
+Date: Tue, 11 Sep 2018 05:32:37 -0400
+Subject: media: v4l: event: Prevent freeing event subscriptions while accessed
+
+From: Sakari Ailus <sakari.ailus@linux.intel.com>
+
+commit ad608fbcf166fec809e402d548761768f602702c upstream.
+
+The event subscriptions are added to the subscribed event list while
+holding a spinlock, but that lock is subsequently released while still
+accessing the subscription object. This makes it possible to unsubscribe
+the event --- and freeing the subscription object's memory --- while
+the subscription object is simultaneously accessed.
+
+Prevent this by adding a mutex to serialise the event subscription and
+unsubscription. This also gives a guarantee to the callback ops that the
+add op has returned before the del op is called.
+
+This change also results in making the elems field less special:
+subscriptions are only added to the event list once they are fully
+initialised.
+
+Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
+Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
+Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+Cc: stable@vger.kernel.org # for 4.14 and up
+Fixes: c3b5b0241f62 ("V4L/DVB: V4L: Events: Add backend")
+Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/media/v4l2-core/v4l2-event.c |   37 +++++++++++++++++------------------
+ drivers/media/v4l2-core/v4l2-fh.c    |    2 +
+ include/media/v4l2-fh.h              |    1 
+ 3 files changed, 22 insertions(+), 18 deletions(-)
+
+--- a/drivers/media/v4l2-core/v4l2-event.c
++++ b/drivers/media/v4l2-core/v4l2-event.c
+@@ -119,14 +119,6 @@ static void __v4l2_event_queue_fh(struct
+       if (sev == NULL)
+               return;
+ 
+-      /*
+-       * If the event has been added to the fh->subscribed list, but its
+-       * add op has not completed yet elems will be 0, treat this as
+-       * not being subscribed.
+-       */
+-      if (!sev->elems)
+-              return;
+-
+       /* Increase event sequence number on fh. */
+       fh->sequence++;
+ 
+@@ -212,6 +204,7 @@ int v4l2_event_subscribe(struct v4l2_fh
+       struct v4l2_subscribed_event *sev, *found_ev;
+       unsigned long flags;
+       unsigned i;
++      int ret = 0;
+ 
+       if (sub->type == V4L2_EVENT_ALL)
+               return -EINVAL;
+@@ -229,31 +222,36 @@ int v4l2_event_subscribe(struct v4l2_fh
+       sev->flags = sub->flags;
+       sev->fh = fh;
+       sev->ops = ops;
++      sev->elems = elems;
++
++      mutex_lock(&fh->subscribe_lock);
+ 
+       spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+       found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
+-      if (!found_ev)
+-              list_add(&sev->list, &fh->subscribed);
+       spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+ 
+       if (found_ev) {
++              /* Already listening */
+               kfree(sev);
+-              return 0; /* Already listening */
++              goto out_unlock;
+       }
+ 
+       if (sev->ops && sev->ops->add) {
+-              int ret = sev->ops->add(sev, elems);
++              ret = sev->ops->add(sev, elems);
+               if (ret) {
+-                      sev->ops = NULL;
+-                      v4l2_event_unsubscribe(fh, sub);
+-                      return ret;
++                      kfree(sev);
++                      goto out_unlock;
+               }
+       }
+ 
+-      /* Mark as ready for use */
+-      sev->elems = elems;
++      spin_lock_irqsave(&fh->vdev->fh_lock, flags);
++      list_add(&sev->list, &fh->subscribed);
++      spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+ 
+-      return 0;
++out_unlock:
++      mutex_unlock(&fh->subscribe_lock);
++
++      return ret;
+ }
+ EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
+ 
+@@ -292,6 +290,8 @@ int v4l2_event_unsubscribe(struct v4l2_f
+               return 0;
+       }
+ 
++      mutex_lock(&fh->subscribe_lock);
++
+       spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+ 
+       sev = v4l2_event_subscribed(fh, sub->type, sub->id);
+@@ -310,6 +310,7 @@ int v4l2_event_unsubscribe(struct v4l2_f
+               sev->ops->del(sev);
+ 
+       kfree(sev);
++      mutex_unlock(&fh->subscribe_lock);
+ 
+       return 0;
+ }
+--- a/drivers/media/v4l2-core/v4l2-fh.c
++++ b/drivers/media/v4l2-core/v4l2-fh.c
+@@ -49,6 +49,7 @@ void v4l2_fh_init(struct v4l2_fh *fh, st
+       INIT_LIST_HEAD(&fh->available);
+       INIT_LIST_HEAD(&fh->subscribed);
+       fh->sequence = -1;
++      mutex_init(&fh->subscribe_lock);
+ }
+ EXPORT_SYMBOL_GPL(v4l2_fh_init);
+ 
+@@ -93,6 +94,7 @@ void v4l2_fh_exit(struct v4l2_fh *fh)
+       if (fh->vdev == NULL)
+               return;
+       v4l2_event_unsubscribe_all(fh);
++      mutex_destroy(&fh->subscribe_lock);
+       fh->vdev = NULL;
+ }
+ EXPORT_SYMBOL_GPL(v4l2_fh_exit);
+--- a/include/media/v4l2-fh.h
++++ b/include/media/v4l2-fh.h
+@@ -43,6 +43,7 @@ struct v4l2_fh {
+       wait_queue_head_t       wait;
+       struct list_head        subscribed; /* Subscribed events */
+       struct list_head        available; /* Dequeueable event */
++      struct mutex            subscribe_lock;
+       unsigned int            navailable;
+       u32                     sequence;
+ 

diff --git a/queue-4.4/series b/queue-4.4/series
index 0451903519fd3c5dc42b6a19d4923f7c60df1adf..2d91c499644d9b7721d0a1b6fc46aba76601a325 100644 (file)
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -70,3 +70,4 @@ hwmon-adt7475-make-adt7475_read_word-return-errors.patch
 i2c-i801-allow-acpi-aml-access-i-o-ports-not-reserved-for-smbus.patch
 arm64-cpufeature-track-32bit-el0-support.patch
 arm64-kvm-sanitize-pstate.m-when-being-set-from-userspace.patch
+media-v4l-event-prevent-freeing-event-subscriptions-while-accessed.patch