From: Chen Zhongjin <chenzhongjin@xxxxxxxxxx> [ Upstream commit a574359e2e71ce16be212df3a082ed60a4bd2c5f ] In dvb_register_frontend(), dvb_register_device() is possible to fail but its return value is ignored. It will cause use-after-free when module is removed, because in dvb_unregister_frontend() it tries to unregister a not registered device. BUG: KASAN: use-after-free in dvb_remove_device+0x18b/0x1f0 [dvb_core] Read of size 4 at addr ffff88800dff4824 by task rmmod/428 CPU: 3 PID: 428 Comm: rmmod Call Trace: <TASK> ... dvb_remove_device+0x18b/0x1f0 [dvb_core] dvb_unregister_frontend+0x7b/0x130 [dvb_core] vidtv_bridge_remove+0x6e/0x160 [dvb_vidtv_bridge] ... Fix this by catching return value of dvb_register_device(). However the fe->refcount can't be put to zero immediately, because there are still modules calling dvb_frontend_detach() when dvb_register_frontend() fails. Link: https://lore.kernel.org/linux-media/20221108033005.169095-1-chenzhongjin@xxxxxxxxxx Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/media/dvb-core/dvb_frontend.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index 258637d762d6..70d07cdcb2a6 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -2985,6 +2985,7 @@ int dvb_register_frontend(struct dvb_adapter *dvb, .name = fe->ops.info.name, #endif }; + int ret; dev_dbg(dvb->device, "%s:\n", __func__); @@ -3018,8 +3019,13 @@ int dvb_register_frontend(struct dvb_adapter *dvb, "DVB: registering adapter %i frontend %i (%s)...\n", fe->dvb->num, fe->id, fe->ops.info.name); - dvb_register_device(fe->dvb, &fepriv->dvbdev, &dvbdev_template, + ret = dvb_register_device(fe->dvb, &fepriv->dvbdev, &dvbdev_template, fe, DVB_DEVICE_FRONTEND, 0); + if (ret) { + dvb_frontend_put(fe); + mutex_unlock(&frontend_mutex); + return ret; + } /* * Initialize the cache to the proper values according with the -- 2.35.1
