2023-10-07 03:32:29

by Dinghao Liu

Subject: [PATCH] [v4] 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 <[email protected]>
---

Changelog:

v2: -Remove the first clk_unregister() instead of nulling priv->clk.

v3: -Simplify ca8210_register_ext_clock().
-Add a ';' after return in ca8210_unregister_ext_clock().

v4: -Remove an unused variable 'ret'.
---
drivers/net/ieee802154/ca8210.c | 17 +++--------------
1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ieee802154/ca8210.c b/drivers/net/ieee802154/ca8210.c
index aebb19f1b3a4..4ec0dab38872 100644
--- 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);
--
2.17.1

2023-10-07 18:48:23

by Stefan Schmidt

Subject: Re: [PATCH] [v4] ieee802154: ca8210: Fix a potential UAF in ca8210_probe

Hello.

On 07.10.23 05:30, Dinghao Liu wrote:
> 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 <[email protected]>
> ---
>
> Changelog:
>
> v2: -Remove the first clk_unregister() instead of nulling priv->clk.
>
> v3: -Simplify ca8210_register_ext_clock().
> -Add a ';' after return in ca8210_unregister_ext_clock().
>
> v4: -Remove an unused variable 'ret'.


This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

regards
Stefan Schmidt