From 2052138b7da52ad5ccaf74f736d00f39a1c9198c Mon Sep 17 00:00:00 2001 From: Zheng Yejian Date: Thu, 9 May 2024 20:44:14 +0800 Subject: [PATCH] media: dvb-usb: Fix unexpected infinite loop in dvb_usb_read_remote_control() Infinite log printing occurs during fuzz test: rc rc1: DViCO FusionHDTV DVB-T USB (LGZ201) as ... ... dvb-usb: schedule remote query interval to 100 msecs. dvb-usb: DViCO FusionHDTV DVB-T USB (LGZ201) successfully initialized ... dvb-usb: bulk message failed: -22 (1/0) dvb-usb: bulk message failed: -22 (1/0) dvb-usb: bulk message failed: -22 (1/0) ... dvb-usb: bulk message failed: -22 (1/0) Looking into the codes, there is a loop in dvb_usb_read_remote_control(), that is in rc_core_dvb_usb_remote_init() create a work that will call dvb_usb_read_remote_control(), and this work will reschedule itself at 'rc_interval' intervals to recursively call dvb_usb_read_remote_control(), see following code snippet: rc_core_dvb_usb_remote_init() { ... INIT_DELAYED_WORK(&d->rc_query_work, dvb_usb_read_remote_control); schedule_delayed_work(&d->rc_query_work, msecs_to_jiffies(rc_interval)); ... } dvb_usb_read_remote_control() { ... err = d->props.rc.core.rc_query(d); if (err) err(...) // Did not return even if query failed schedule_delayed_work(&d->rc_query_work, msecs_to_jiffies(rc_interval)); } When the infinite log printing occurs, the query callback 'd->props.rc.core.rc_query' is cxusb_rc_query(). And the log is due to the failure of finding a valid 'generic_bulk_ctrl_endpoint' in usb_bulk_msg(), see following code snippet: cxusb_rc_query() { cxusb_ctrl_msg() { dvb_usb_generic_rw() { ret = usb_bulk_msg(d->udev, usb_sndbulkpipe(d->udev, d->props.generic_bulk_ctrl_endpoint),...); if (ret) err("bulk message failed: %d (%d/%d)",ret,wlen,actlen); ... } ... } By analyzing the corresponding USB descriptor, it shows that the bNumEndpoints is 0 in its interface descriptor, but the 'generic_bulk_ctrl_endpoint' is 1, that means user don't configure a valid endpoint for 'generic_bulk_ctrl_endpoint', therefore this 'invalid' USB device should be rejected before it calls into dvb_usb_read_remote_control(). To fix it, we need to add endpoint check for 'generic_bulk_ctrl_endpoint'. And as Sean suggested, the same check and clear halts should be done for 'generic_bulk_ctrl_endpoint_response'. So introduce dvb_usb_check_bulk_endpoint() to do it for both of them. Fixes: 4d43e13f723e ("V4L/DVB (4643): Multi-input patch for DVB-USB device") Signed-off-by: Zheng Yejian Signed-off-by: Sean Young Signed-off-by: Hans Verkuil --- drivers/media/usb/dvb-usb/dvb-usb-init.c | 35 +++++++++++++++++++++--- 1 file changed, 31 insertions(+), 4 deletions(-) diff --git a/drivers/media/usb/dvb-usb/dvb-usb-init.c b/drivers/media/usb/dvb-usb/dvb-usb-init.c index fbf58012becd..22d83ac18eb7 100644 --- a/drivers/media/usb/dvb-usb/dvb-usb-init.c +++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c @@ -23,11 +23,40 @@ static int dvb_usb_force_pid_filter_usage; module_param_named(force_pid_filter_usage, dvb_usb_force_pid_filter_usage, int, 0444); MODULE_PARM_DESC(force_pid_filter_usage, "force all dvb-usb-devices to use a PID filter, if any (default: 0)."); +static int dvb_usb_check_bulk_endpoint(struct dvb_usb_device *d, u8 endpoint) +{ + if (endpoint) { + int ret; + + ret = usb_pipe_type_check(d->udev, usb_sndbulkpipe(d->udev, endpoint)); + if (ret) + return ret; + ret = usb_pipe_type_check(d->udev, usb_rcvbulkpipe(d->udev, endpoint)); + if (ret) + return ret; + } + return 0; +} + +static void dvb_usb_clear_halt(struct dvb_usb_device *d, u8 endpoint) +{ + if (endpoint) { + usb_clear_halt(d->udev, usb_sndbulkpipe(d->udev, endpoint)); + usb_clear_halt(d->udev, usb_rcvbulkpipe(d->udev, endpoint)); + } +} + static int dvb_usb_adapter_init(struct dvb_usb_device *d, short *adapter_nrs) { struct dvb_usb_adapter *adap; int ret, n, o; + ret = dvb_usb_check_bulk_endpoint(d, d->props.generic_bulk_ctrl_endpoint); + if (ret) + return ret; + ret = dvb_usb_check_bulk_endpoint(d, d->props.generic_bulk_ctrl_endpoint_response); + if (ret) + return ret; for (n = 0; n < d->props.num_adapters; n++) { adap = &d->adapter[n]; adap->dev = d; @@ -103,10 +132,8 @@ static int dvb_usb_adapter_init(struct dvb_usb_device *d, short *adapter_nrs) * when reloading the driver w/o replugging the device * sometimes a timeout occurs, this helps */ - if (d->props.generic_bulk_ctrl_endpoint != 0) { - usb_clear_halt(d->udev, usb_sndbulkpipe(d->udev, d->props.generic_bulk_ctrl_endpoint)); - usb_clear_halt(d->udev, usb_rcvbulkpipe(d->udev, d->props.generic_bulk_ctrl_endpoint)); - } + dvb_usb_clear_halt(d, d->props.generic_bulk_ctrl_endpoint); + dvb_usb_clear_halt(d, d->props.generic_bulk_ctrl_endpoint_response); return 0;