| Message ID | 20230925072423.24772-1-dinghao.liu@zju.edu.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ieee802154: ca8210: Fix a potential UAF in ca8210_probe | expand |
Hi Dinghao, dinghao.liu@zju.edu.cn wrote on Mon, 25 Sep 2023 15:24:22 +0800: > 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@zju.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; This function is a bit convoluted. You could just return the result of of_clk_add_provider() (keep the printk's if you want, they don't seem very useful) and let ca8210_unregister_ext_clock() do the cleanup. > 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)) Does not look useful as you are enforcing priv->clock to be valid or NULL, it cannot be an error code. Thanks, Miquèl
Hi Miquèl, > > 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; > > This function is a bit convoluted. You could just return the result of > of_clk_add_provider() (keep the printk's if you want, they don't seem > very useful) and let ca8210_unregister_ext_clock() do the cleanup. Thanks for your advice! I will resend a new patch as suggested. > > > 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)) > > Does not look useful as you are enforcing priv->clock to be valid or > NULL, it cannot be an error code. I find that ca8210_register_ext_clock() uses IS_ERR to check priv->clk after calling clk_register_fixed_rate(). So I think priv->clk could be a non-null pointer even on failure. And a null pointer check may miss this case in ca8210_unregister_ext_clock(). Regards, Dinghao
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);
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@zju.edu.cn> --- drivers/net/ieee802154/ca8210.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)