This is a note to let you know that I've just added the patch titled
media: edia: dvbdev: fix a use-after-free
to the 6.6-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-edia-dvbdev-fix-a-use-after-free.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a231df8176c8348e5747e91c5c77fcf9828172f1
Author: Zhipeng Lu <alexious@xxxxxxxxxx>
Date: Sat Feb 3 14:40:43 2024 +0100
media: edia: dvbdev: fix a use-after-free
[ Upstream commit 8c64f4cdf4e6cc5682c52523713af8c39c94e6d5 ]
In dvb_register_device, *pdvbdev is set equal to dvbdev, which is freed
in several error-handling paths. However, *pdvbdev is not set to NULL
after dvbdev's deallocation, causing use-after-frees in many places,
for example, in the following call chain:
budget_register
|-> dvb_dmxdev_init
|-> dvb_register_device
|-> dvb_dmxdev_release
|-> dvb_unregister_device
|-> dvb_remove_device
|-> dvb_device_put
|-> kref_put
When calling dvb_unregister_device, dmxdev->dvbdev (i.e. *pdvbdev in
dvb_register_device) could point to memory that had been freed in
dvb_register_device. Thereafter, this pointer is transferred to
kref_put and triggering a use-after-free.
Link: https://lore.kernel.org/linux-media/20240203134046.3120099-1-alexious@xxxxxxxxxx
Fixes: b61901024776 ("V4L/DVB (5244): Dvbdev: fix illegal re-usage of fileoperations struct")
Signed-off-by: Zhipeng Lu <alexious@xxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index 49f0eb7d0b9d3..733d0bc4b4cc3 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -490,6 +490,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
dvbdevfops = kmemdup(template->fops, sizeof(*dvbdevfops), GFP_KERNEL);
if (!dvbdevfops) {
kfree(dvbdev);
+ *pdvbdev = NULL;
mutex_unlock(&dvbdev_register_lock);
return -ENOMEM;
}
@@ -498,6 +499,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
if (!new_node) {
kfree(dvbdevfops);
kfree(dvbdev);
+ *pdvbdev = NULL;
mutex_unlock(&dvbdev_register_lock);
return -ENOMEM;
}
@@ -531,6 +533,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
}
list_del(&dvbdev->list_head);
kfree(dvbdev);
+ *pdvbdev = NULL;
up_write(&minor_rwsem);
mutex_unlock(&dvbdev_register_lock);
return -EINVAL;
@@ -553,6 +556,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
dvb_media_device_free(dvbdev);
list_del(&dvbdev->list_head);
kfree(dvbdev);
+ *pdvbdev = NULL;
mutex_unlock(&dvbdev_register_lock);
return ret;
}
@@ -571,6 +575,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
dvb_media_device_free(dvbdev);
list_del(&dvbdev->list_head);
kfree(dvbdev);
+ *pdvbdev = NULL;
mutex_unlock(&dvbdev_register_lock);
return PTR_ERR(clsdev);
}
