Messages in this thread Patch in this message | | | Subject | Re: [PATCH] media: mxl111sf: change mutex_init() location | From | Pavel Skripkin <> | Date | Sun, 15 Aug 2021 12:06:16 +0300 |
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On 8/15/21 11:49 AM, Pavel Skripkin wrote: > On 8/15/21 11:37 AM, Sean Young wrote: >> On Sat, Jul 31, 2021 at 12:38:29AM +0300, Pavel Skripkin wrote: >>> 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_frontend_attach_atsc_mh() calls mxl111sf_ctrl_msg() >>> internally we need to initialize state->msg_lock in it to make lockdep >>> happy. >> >> What about the other frontends like mxl111sf_frontend_attach_dvbt? They >> no longer initialize the mutex. >> > Good point. I see, that all other frontends also call > mxl111sf_ctrl_msg() inside ->frontend_attach() call. > > I think, that fixing dvb-usb core is not good idea, so, I will add > mutex_init() call inside all frontends, which use mxl111sf_init(). > > What do you think about it? > >
Something like this should work. Helper is just to not copy-paste code parts. Build tested against v5.14-rc5
diff --git a/drivers/media/usb/dvb-usb-v2/mxl111sf.c b/drivers/media/usb/dvb-usb-v2/mxl111sf.c index 7865fa0a8295..db1ad3815cd5 100644 --- a/drivers/media/usb/dvb-usb-v2/mxl111sf.c +++ b/drivers/media/usb/dvb-usb-v2/mxl111sf.c @@ -49,6 +49,13 @@ MODULE_PARM_DESC(rfswitch, "force rf switch position (0=auto, 1=ext, 2=int).");
DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
+static inline void mxl111sf_init_msg_mutex(struct dvb_usb_adapter *adap) +{ + struct mxl111sf_state *state = d_to_priv(adap_to_d(adap)); + + mutex_init(&state->msg_lock); +} + int mxl111sf_ctrl_msg(struct mxl111sf_state *state, u8 cmd, u8 *wbuf, int wlen, u8 *rbuf, int rlen) { @@ -931,8 +938,6 @@ 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"); @@ -963,16 +968,19 @@ static int mxl111sf_init(struct dvb_usb_device *d)
static int mxl111sf_frontend_attach_dvbt(struct dvb_usb_adapter *adap) { + mxl111sf_init_msg_mutex(adap); return mxl111sf_attach_demod(adap, 0); }
static int mxl111sf_frontend_attach_atsc(struct dvb_usb_adapter *adap) { + mxl111sf_init_msg_mutex(adap); return mxl111sf_lgdt3305_frontend_attach(adap, 0); }
static int mxl111sf_frontend_attach_mh(struct dvb_usb_adapter *adap) { + mxl111sf_init_msg_mutex(adap); return mxl111sf_lg2160_frontend_attach(adap, 0); }
@@ -981,6 +989,7 @@ static int mxl111sf_frontend_attach_atsc_mh(struct dvb_usb_adapter *adap) int ret; pr_debug("%s\n", __func__);
+ mxl111sf_init_msg_mutex(adap); ret = mxl111sf_lgdt3305_frontend_attach(adap, 0); if (ret < 0) return ret; @@ -1001,6 +1010,7 @@ static int mxl111sf_frontend_attach_mercury(struct dvb_usb_adapter *adap) int ret; pr_debug("%s\n", __func__);
+ mxl111sf_init_msg_mutex(adap); ret = mxl111sf_lgdt3305_frontend_attach(adap, 0); if (ret < 0) return ret; @@ -1021,6 +1031,7 @@ static int mxl111sf_frontend_attach_mercury_mh(struct dvb_usb_adapter *adap) int ret; pr_debug("%s\n", __func__);
+ mxl111sf_init_msg_mutex(adap); ret = mxl111sf_attach_demod(adap, 0); if (ret < 0) return ret;
With regards, Pavel Skripkin
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