This is a note to let you know that I've just added the patch titled
media: dvb-core: Fix ignored return value in dvb_register_frontend()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-dvb-core-fix-ignored-return-value-in-dvb_regis.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6f9625999b5d9dccc48b3e6932359f08fc72a8c4
Author: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
Date: Tue Nov 8 03:30:05 2022 +0000
media: dvb-core: Fix ignored return value in dvb_register_frontend()
[ 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>
diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index 8a61150ee249..1768c1b515b3 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -2956,6 +2956,7 @@ int dvb_register_frontend(struct dvb_adapter *dvb,
.name = fe->ops.info.name,
#endif
};
+ int ret;
dev_dbg(dvb->device, "%s:\n", __func__);
@@ -2989,8 +2990,13 @@ 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
