ieee802154: ca8210: Fix a potential UAF in ca8210_probe

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>
Message-ID: <20231007033049.22353-1-dinghao.liu@zju.edu.cn>
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

diff --git a/drivers/net/ieee802154/ca8210.c b/drivers/net/ieee802154/ca8210.c
index aebb19f1b3a41ee2d3a39590715df63d85a983ff..4ec0dab388729950b79093d18236639d0583cd2a 100644 (file)
--- a/drivers/net/ieee802154/ca8210.c
+++ b/drivers/net/ieee802154/ca8210.c
@@ -2740,7 +2740,6 @@ static int ca8210_register_ext_clock(struct spi_device *spi)
        struct device_node *np = spi->dev.of_node;
        struct ca8210_priv *priv = spi_get_drvdata(spi);
        struct ca8210_platform_data *pdata = spi->dev.platform_data;
-       int ret = 0;
 
        if (!np)
                return -EFAULT;
@@ -2757,18 +2756,8 @@ static int ca8210_register_ext_clock(struct spi_device *spi)
                dev_crit(&spi->dev, "Failed to register external clk\n");
                return PTR_ERR(priv->clk);
        }
-       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"
-               );
-       } else {
-               dev_info(&spi->dev, "External clock set as clock provider\n");
-       }
 
-       return ret;
+       return of_clk_add_provider(np, of_clk_src_simple_get, priv->clk);
 }
 
 /**
@@ -2780,8 +2769,8 @@ static void ca8210_unregister_ext_clock(struct spi_device *spi)
 {
        struct ca8210_priv *priv = spi_get_drvdata(spi);
 
-       if (!priv->clk)
-               return
+       if (IS_ERR_OR_NULL(priv->clk))
+               return;
 
        of_clk_del_provider(spi->dev.of_node);
        clk_unregister(priv->clk);