[PATCH] net: wan: fsl_ucc_hdlc: release resources on remove

[Guangshuo Li <lgs201920130244@gmail.com>]

ucc_hdlc_probe() allocates and registers an HDLC netdev and, when the
TDM interface is enabled, separately allocates struct ucc_tdm. The
probe failure paths release these resources, but the remove path does
not.

As a result, the registered HDLC netdev can outlive its private data
and retain a dangling private pointer. The separately allocated TDM
data is also leaked when a TDM-mode device is removed.

Unregister the HDLC device before releasing the UCC and DMA resources,
free the netdev after the hardware resources have been cleaned up, and
free the TDM data before releasing the private data.

This issue was found by manual code inspection.

Fixes: c19b6d246a35 ("drivers/net: support hdlc function for QE-UCC")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/net/wan/fsl_ucc_hdlc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wan/fsl_ucc_hdlc.c b/drivers/net/wan/fsl_ucc_hdlc.c
index 809f21fb93f5..ffc8b989e33a 100644
--- a/drivers/net/wan/fsl_ucc_hdlc.c
+++ b/drivers/net/wan/fsl_ucc_hdlc.c
@@ -1254,6 +1254,7 @@ static int ucc_hdlc_probe(struct platform_device *pdev)
 static void ucc_hdlc_remove(struct platform_device *pdev)
 {
 	struct ucc_hdlc_private *priv = dev_get_drvdata(&pdev->dev);
+	unregister_hdlc_device(priv->ndev);
 
 	uhdlc_memclean(priv);
 
@@ -1266,6 +1267,8 @@ static void ucc_hdlc_remove(struct platform_device *pdev)
 		iounmap(priv->utdm->siram);
 		priv->utdm->siram = NULL;
 	}
+	free_netdev(priv->ndev);
+	kfree(priv->utdm);
 	kfree(priv);
 
 	dev_info(&pdev->dev, "UCC based hdlc module removed\n");
-- 
2.43.0