vidtv: move kfree(dvb) to vidtv_bridge_dev_release()

Commit Message

Hans Verkuil Sept. 14, 2021, 7:21 a.m. UTC

Adding kfree(dvb) to vidtv_bridge_remove() will remove the memory
too soon: if an application still has an open filehandle to the device
when the driver is unloaded, then when that filehandle is closed, a
use-after-free access takes place to the freed memory.

Move the kfree(dvb) to vidtv_bridge_dev_release() instead.

Signed-off-by: Hans Verkuil <[e-mail]>
Fixes: 28bcf7de1bfd ("media: vidtv: Fix memory leak in remove")
---

Patch

diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
index 0f6d998d18dc..82620613d56b 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
@@ -557,7 +557,6 @@  static int vidtv_bridge_remove(struct platform_device *pdev)
 	dvb_dmxdev_release(&dvb->dmx_dev);
 	dvb_dmx_release(&dvb->demux);
 	dvb_unregister_adapter(&dvb->adapter);
-	kfree(dvb);
 	dev_info(&pdev->dev, "Successfully removed vidtv\n");

 	return 0;
@@ -565,6 +564,10 @@  static int vidtv_bridge_remove(struct platform_device *pdev)

 static void vidtv_bridge_dev_release(struct device *dev)
 {
+	struct vidtv_dvb *dvb;
+
+	dvb = dev_get_drvdata(dev);
+	kfree(dvb);
 }

 static struct platform_device vidtv_bridge_dev = {