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Message-Id: <20240203134046.3120099-1-alexious@zju.edu.cn>
Date: Sat, 3 Feb 2024 21:40:43 +0800
From: Zhipeng Lu <alexious@....edu.cn>
To: alexious@....edu.cn
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
Hans Verkuil <hverkuil-cisco@...all.nl>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Hyunwoo Kim <imv4bel@...il.com>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Marcel Siegert <mws@...uxtv.org>,
linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] edia: dvbdev: fix a use-after-free
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.
Fixes: b61901024776 ("V4L/DVB (5244): Dvbdev: fix illegal re-usage of fileoperations struct")
Signed-off-by: Zhipeng Lu <alexious@....edu.cn>
---
drivers/media/dvb-core/dvbdev.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index 305bb21d843c..a027b9110793 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -488,6 +488,7 @@ 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;
}
@@ -496,6 +497,7 @@ 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;
}
@@ -529,6 +531,7 @@ 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;
@@ -551,6 +554,7 @@ 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;
}
@@ -569,6 +573,7 @@ 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);
}
--
2.34.1
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