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media: edia: dvbdev: fix a use-after-free

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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@zju.edu.cn
Fixes: b619010247 ("V4L/DVB (5244): Dvbdev: fix illegal re-usage of fileoperations struct")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Zhipeng Lu 2024-02-03 14:40:43 +01:00 committed by Mauro Carvalho Chehab
parent 9651d3d2d6
commit 8c64f4cdf4
1 changed files with 5 additions and 0 deletions
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5
drivers/media/dvb-core/dvbdev.c
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@ -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);
}