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Subject: media: dvb-usb: Fix unexpected infinite loop in
dvb_usb_read_remote_control()
Author: Zheng Yejian <zhengyeji...@huawei.com>
Date: Thu May 9 20:44:14 2024 +0800
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 <zhengyeji...@huawei.com>
Signed-off-by: Sean Young <s...@mess.org>
Signed-off-by: Hans Verkuil <hverkuil-ci...@xs4all.nl>
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;
