[PATCH] [v2] ieee802154: ca8210: Fix a potential UAF in ca8210_probe

[Dinghao Liu <dinghao.liu@zju.edu.cn>]

If of_clk_add_provider() fails in ca8210_register_ext_clock(),
it calls clk_unregister() to release priv->clk and returns an
error. However, the caller ca8210_probe() then calls ca8210_remove(),
where priv->clk is freed again in ca8210_unregister_ext_clock(). In
this case, a use-after-free may happen in the second time we call
clk_unregister().

Fix this by removing the first clk_unregister(). Also, priv->clk could
be an error code on failure of clk_register_fixed_rate(). Use
IS_ERR_OR_NULL to catch this case in ca8210_unregister_ext_clock().

Fixes: ded845a781a5 ("ieee802154: Add CA8210 IEEE 802.15.4 device driver")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
---

Changelog:

v2: -Remove the first clk_unregister() instead of nulling priv->clk.
---
 drivers/net/ieee802154/ca8210.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ieee802154/ca8210.c b/drivers/net/ieee802154/ca8210.c
index aebb19f1b3a4..b35c6f59bd1a 100644
--- a/drivers/net/ieee802154/ca8210.c
+++ b/drivers/net/ieee802154/ca8210.c
@@ -2759,7 +2759,6 @@ static int ca8210_register_ext_clock(struct spi_device *spi)
 	}
 	ret = of_clk_add_provider(np, of_clk_src_simple_get, priv->clk);
 	if (ret) {
-		clk_unregister(priv->clk);
 		dev_crit(
 			&spi->dev,
 			"Failed to register external clock as clock provider\n"
@@ -2780,7 +2779,7 @@ static void ca8210_unregister_ext_clock(struct spi_device *spi)
 {
 	struct ca8210_priv *priv = spi_get_drvdata(spi);
 
-	if (!priv->clk)
+	if (IS_ERR_OR_NULL(priv->clk))
 		return
 
 	of_clk_del_provider(spi->dev.of_node);
-- 
2.17.1