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media fixes for v4.19-rc6 

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Merge tag 'media/v4.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Mauro writes:
  "media fixes for v4.19-rc6"

* tag 'media/v4.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  media: v4l: event: Prevent freeing event subscriptions while accessed
This commit is contained in:
Greg Kroah-Hartman 2018-10-03 04:23:46 -07:00
parent 5b372600cc ad608fbcf1
commit 6bebe37927
3 changed files with 26 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/media/v4l2-core/v4l2-event.c
View File

@ -115,14 +115,6 @@ static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *e
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++;
@ -208,6 +200,7 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
struct v4l2_subscribed_event *sev, *found_ev;
unsigned long flags;
unsigned i;
int ret = 0;
if (sub->type == V4L2_EVENT_ALL)
return -EINVAL;
@ -225,31 +218,36 @@ int v4l2_event_subscribe(struct v4l2_fh *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 */
kvfree(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;
kvfree(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);
@ -288,6 +286,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
return 0;
}
mutex_lock(&fh->subscribe_lock);
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
sev = v4l2_event_subscribed(fh, sub->type, sub->id);
@ -305,6 +305,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
if (sev && sev->ops && sev->ops->del)
sev->ops->del(sev);
mutex_unlock(&fh->subscribe_lock);
kvfree(sev);
return 0;

2
drivers/media/v4l2-core/v4l2-fh.c
View File

@ -45,6 +45,7 @@ void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
INIT_LIST_HEAD(&fh->available);
INIT_LIST_HEAD(&fh->subscribed);
fh->sequence = -1;
mutex_init(&fh->subscribe_lock);
}
EXPORT_SYMBOL_GPL(v4l2_fh_init);
@ -90,6 +91,7 @@ void v4l2_fh_exit(struct v4l2_fh *fh)
return;
v4l_disable_media_source(fh->vdev);
v4l2_event_unsubscribe_all(fh);
mutex_destroy(&fh->subscribe_lock);
fh->vdev = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_fh_exit);

4
include/media/v4l2-fh.h
View File

@ -38,10 +38,13 @@ struct v4l2_ctrl_handler;
* @prio: priority of the file handler, as defined by &enum v4l2_priority
*
* @wait: event' s wait queue
* @subscribe_lock: serialise changes to the subscribed list; guarantee that
* the add and del event callbacks are orderly called
* @subscribed: list of subscribed events
* @available: list of events waiting to be dequeued
* @navailable: number of available events at @available list
* @sequence: event sequence number
*
* @m2m_ctx: pointer to &struct v4l2_m2m_ctx
*/
struct v4l2_fh {
@ -52,6 +55,7 @@ struct v4l2_fh {
/* Events */
wait_queue_head_t wait;
struct mutex subscribe_lock;
struct list_head subscribed;
struct list_head available;
unsigned int navailable;