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V4L/DVB (5400): Core: fix several locking related problems
Fix several instances of dvb-core functions using mutex_lock_interruptible and returning -ERESTARTSYS where the calling function will either never retry or never check the return value. These cause a race condition with dvb_dmxdev_filter_free and dvb_dvr_release, both of which are filesystem release functions whose return value is ignored and will never be retried. When this happens it becomes impossible to open dvr0 again (-EBUSY) since it has not been released properly. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-By: Johannes Stezenbach <js@linuxtv.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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parent
b10fece583
commit
c278850206
3 changed files with 13 additions and 29 deletions
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@ -180,8 +180,7 @@ static int dvb_dvr_release(struct inode *inode, struct file *file)
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struct dvb_device *dvbdev = file->private_data;
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struct dmxdev *dmxdev = dvbdev->priv;
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if (mutex_lock_interruptible(&dmxdev->mutex))
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return -ERESTARTSYS;
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mutex_lock(&dmxdev->mutex);
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if ((file->f_flags & O_ACCMODE) == O_WRONLY) {
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dmxdev->demux->disconnect_frontend(dmxdev->demux);
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@ -673,13 +672,8 @@ static int dvb_demux_open(struct inode *inode, struct file *file)
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static int dvb_dmxdev_filter_free(struct dmxdev *dmxdev,
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struct dmxdev_filter *dmxdevfilter)
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{
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if (mutex_lock_interruptible(&dmxdev->mutex))
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return -ERESTARTSYS;
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if (mutex_lock_interruptible(&dmxdevfilter->mutex)) {
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mutex_unlock(&dmxdev->mutex);
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return -ERESTARTSYS;
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}
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mutex_lock(&dmxdev->mutex);
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mutex_lock(&dmxdevfilter->mutex);
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dvb_dmxdev_filter_stop(dmxdevfilter);
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dvb_dmxdev_filter_reset(dmxdevfilter);
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@ -673,8 +673,7 @@ static int dmx_ts_feed_stop_filtering(struct dmx_ts_feed *ts_feed)
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struct dvb_demux *demux = feed->demux;
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int ret;
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if (mutex_lock_interruptible(&demux->mutex))
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return -ERESTARTSYS;
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mutex_lock(&demux->mutex);
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if (feed->state < DMX_STATE_GO) {
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mutex_unlock(&demux->mutex);
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@ -748,8 +747,7 @@ static int dvbdmx_release_ts_feed(struct dmx_demux *dmx,
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struct dvb_demux *demux = (struct dvb_demux *)dmx;
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struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed;
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if (mutex_lock_interruptible(&demux->mutex))
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return -ERESTARTSYS;
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mutex_lock(&demux->mutex);
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if (feed->state == DMX_STATE_FREE) {
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mutex_unlock(&demux->mutex);
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@ -916,8 +914,7 @@ static int dmx_section_feed_stop_filtering(struct dmx_section_feed *feed)
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struct dvb_demux *dvbdmx = dvbdmxfeed->demux;
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int ret;
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if (mutex_lock_interruptible(&dvbdmx->mutex))
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return -ERESTARTSYS;
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mutex_lock(&dvbdmx->mutex);
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if (!dvbdmx->stop_feed) {
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mutex_unlock(&dvbdmx->mutex);
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@ -942,8 +939,7 @@ static int dmx_section_feed_release_filter(struct dmx_section_feed *feed,
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struct dvb_demux_feed *dvbdmxfeed = (struct dvb_demux_feed *)feed;
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struct dvb_demux *dvbdmx = dvbdmxfeed->demux;
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if (mutex_lock_interruptible(&dvbdmx->mutex))
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return -ERESTARTSYS;
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mutex_lock(&dvbdmx->mutex);
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if (dvbdmxfilter->feed != dvbdmxfeed) {
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mutex_unlock(&dvbdmx->mutex);
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@ -1016,8 +1012,7 @@ static int dvbdmx_release_section_feed(struct dmx_demux *demux,
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struct dvb_demux_feed *dvbdmxfeed = (struct dvb_demux_feed *)feed;
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struct dvb_demux *dvbdmx = (struct dvb_demux *)demux;
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if (mutex_lock_interruptible(&dvbdmx->mutex))
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return -ERESTARTSYS;
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mutex_lock(&dvbdmx->mutex);
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if (dvbdmxfeed->state == DMX_STATE_FREE) {
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mutex_unlock(&dvbdmx->mutex);
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@ -1126,8 +1121,7 @@ static int dvbdmx_connect_frontend(struct dmx_demux *demux,
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if (demux->frontend)
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return -EINVAL;
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if (mutex_lock_interruptible(&dvbdemux->mutex))
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return -ERESTARTSYS;
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mutex_lock(&dvbdemux->mutex);
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demux->frontend = frontend;
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mutex_unlock(&dvbdemux->mutex);
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@ -1138,8 +1132,7 @@ static int dvbdmx_disconnect_frontend(struct dmx_demux *demux)
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{
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struct dvb_demux *dvbdemux = (struct dvb_demux *)demux;
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if (mutex_lock_interruptible(&dvbdemux->mutex))
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return -ERESTARTSYS;
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mutex_lock(&dvbdemux->mutex);
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demux->frontend = NULL;
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mutex_unlock(&dvbdemux->mutex);
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@ -203,8 +203,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
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int id;
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if (mutex_lock_interruptible(&dvbdev_register_lock))
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return -ERESTARTSYS;
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mutex_lock(&dvbdev_register_lock);
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if ((id = dvbdev_get_free_id (adap, type)) < 0){
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mutex_unlock(&dvbdev_register_lock);
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@ -294,8 +293,7 @@ int dvb_register_adapter(struct dvb_adapter *adap, const char *name, struct modu
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{
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int num;
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if (mutex_lock_interruptible(&dvbdev_register_lock))
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return -ERESTARTSYS;
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mutex_lock(&dvbdev_register_lock);
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if ((num = dvbdev_get_free_adapter_num ()) < 0) {
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mutex_unlock(&dvbdev_register_lock);
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@ -323,8 +321,7 @@ EXPORT_SYMBOL(dvb_register_adapter);
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int dvb_unregister_adapter(struct dvb_adapter *adap)
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{
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if (mutex_lock_interruptible(&dvbdev_register_lock))
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return -ERESTARTSYS;
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mutex_lock(&dvbdev_register_lock);
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list_del (&adap->list_head);
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mutex_unlock(&dvbdev_register_lock);
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return 0;
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