[PATCH v3] media: mxl111sf: change mutex_init() location

Pavel Skripkin
2021-08-19T10:43:03Z

Syzbot reported, that mxl111sf_ctrl_msg() uses uninitialized
mutex. The problem was in wrong mutex_init() location.

Previous mutex_init(&state->msg_lock) call was in ->init() function, but
dvb_usbv2_init() has this order of calls:

dvb_usbv2_init()
dvb_usbv2_adapter_init()
dvb_usbv2_adapter_frontend_init()
props->frontend_attach()

props->init()

Since mxl111sf_* devices call mxl111sf_ctrl_msg() in ->frontend_attach()
internally we need to initialize state->msg_lock before
frontend_attach(). To achieve it, ->probe() call added to all mxl111sf_*
devices, which will simply initiaize mutex.

Reported-and-tested-by: syzbot+5ca0bf339f13c4243001@syzkaller.appspotmail.com
Fixes: 8572211842af ("[media] mxl111sf: convert to new DVB USB")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---

Changes in v3:
I forgot to remove mutex_init() call from ->init()

Changes in v2:
Addressed same bug in all mxl111sf_* devices by adding ->probe
call

---
drivers/media/usb/dvb-usb-v2/mxl111sf.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/dvb-usb-v2/mxl111sf.c b/drivers/media/usb/dvb-usb-v2/mxl111sf.c
index 7865fa0a8295..cd5861a30b6f 100644
--- a/drivers/media/usb/dvb-usb-v2/mxl111sf.c
+++ b/drivers/media/usb/dvb-usb-v2/mxl111sf.c
@@ -931,8 +931,6 @@ static int mxl111sf_init(struct dvb_usb_device *d)
.len = sizeof(eeprom), .buf = eeprom },
};

- mutex_init(&state->msg_lock);
-
ret = get_chip_info(state);
if (mxl_fail(ret))
pr_err("failed to get chip info during probe");
@@ -1074,6 +1072,14 @@ static int mxl111sf_get_stream_config_dvbt(struct dvb_frontend *fe,
return 0;
}

+static int mxl111sf_probe(struct dvb_usb_device *dev)
+{
+ struct mxl111sf_state *state = d_to_priv(dev);
+
+ mutex_init(&state->msg_lock);
+ return 0;
+}
+
static struct dvb_usb_device_properties mxl111sf_props_dvbt = {
.driver_name = KBUILD_MODNAME,
.owner = THIS_MODULE,
@@ -1083,6 +1089,7 @@ static struct dvb_usb_device_properties mxl111sf_props_dvbt = {
.generic_bulk_ctrl_endpoint = 0x02,
.generic_bulk_ctrl_endpoint_response = 0x81,

+ .probe = mxl111sf_probe,
.i2c_algo = &mxl111sf_i2c_algo,
.frontend_attach = mxl111sf_frontend_attach_dvbt,
.tuner_attach = mxl111sf_attach_tuner,
@@ -1124,6 +1131,7 @@ static struct dvb_usb_device_properties mxl111sf_props_atsc = {
.generic_bulk_ctrl_endpoint = 0x02,
.generic_bulk_ctrl_endpoint_response = 0x81,

+ .probe = mxl111sf_probe,
.i2c_algo = &mxl111sf_i2c_algo,
.frontend_attach = mxl111sf_frontend_attach_atsc,
.tuner_attach = mxl111sf_attach_tuner,
@@ -1165,6 +1173,7 @@ static struct dvb_usb_device_properties mxl111sf_props_mh = {
.generic_bulk_ctrl_endpoint = 0x02,
.generic_bulk_ctrl_endpoint_response = 0x81,

+ .probe = mxl111sf_probe,
.i2c_algo = &mxl111sf_i2c_algo,
.frontend_attach = mxl111sf_frontend_attach_mh,
.tuner_attach = mxl111sf_attach_tuner,
@@ -1233,6 +1242,7 @@ static struct dvb_usb_device_properties mxl111sf_props_atsc_mh = {
.generic_bulk_ctrl_endpoint = 0x02,
.generic_bulk_ctrl_endpoint_response = 0x81,

+ .probe = mxl111sf_probe,
.i2c_algo = &mxl111sf_i2c_algo,
.frontend_attach = mxl111sf_frontend_attach_atsc_mh,
.tuner_attach = mxl111sf_attach_tuner,
@@ -1311,6 +1321,7 @@ static struct dvb_usb_device_properties mxl111sf_props_mercury = {
.generic_bulk_ctrl_endpoint = 0x02,
.generic_bulk_ctrl_endpoint_response = 0x81,

+ .probe = mxl111sf_probe,
.i2c_algo = &mxl111sf_i2c_algo,
.frontend_attach = mxl111sf_frontend_attach_mercury,
.tuner_attach = mxl111sf_attach_tuner,
@@ -1381,6 +1392,7 @@ static struct dvb_usb_device_properties mxl111sf_props_mercury_mh = {
.generic_bulk_ctrl_endpoint = 0x02,
.generic_bulk_ctrl_endpoint_response = 0x81,

+ .probe = mxl111sf_probe,
.i2c_algo = &mxl111sf_i2c_algo,
.frontend_attach = mxl111sf_frontend_attach_mercury_mh,
.tuner_attach = mxl111sf_attach_tuner,
--
2.32.0