linux-kernel - [PATCH] ieee802154: ca8210: Fix a potential UAF in ca8210

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Date:   Mon, 25 Sep 2023 15:24:22 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn
Cc:     Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@...enfreihafen.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Harry Morris <harrymorris12@...il.com>,
        linux-wpan@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] 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 nulling priv->clk after the first clk_unregister(). Also
refine the pointer checking in ca8210_unregister_ext_clock().

Fixes: ded845a781a5 ("ieee802154: Add CA8210 IEEE 802.15.4 device driver")
Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---
 drivers/net/ieee802154/ca8210.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ieee802154/ca8210.c b/drivers/net/ieee802154/ca8210.c
index aebb19f1b3a4..1d545879c000 100644
--- a/drivers/net/ieee802154/ca8210.c
+++ b/drivers/net/ieee802154/ca8210.c
@@ -2760,6 +2760,7 @@ 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);
+		priv->clk = NULL;
 		dev_crit(
 			&spi->dev,
 			"Failed to register external clock as clock provider\n"
@@ -2780,7 +2781,7 @@ 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