Messages in this thread | | | Date | Tue, 15 Nov 2022 14:36:34 +0100 | From | Andrew Lunn <> | Subject | Re: [PATCH] net: mdio-ipq4019: fix possible invalid pointer dereference |
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On Tue, Nov 15, 2022 at 12:50:28PM +0800, Hui Tang wrote: > priv->eth_ldo_rdy is saved the return value of devm_ioremap_resource(), > which !IS_ERR() should be used to check. > > Fixes: 23a890d493e3 ("net: mdio: Add the reset function for IPQ MDIO driver") > Signed-off-by: Hui Tang <tanghui20@huawei.com> > --- > drivers/net/mdio/mdio-ipq4019.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/mdio/mdio-ipq4019.c b/drivers/net/mdio/mdio-ipq4019.c > index 4eba5a91075c..d7a1f7c56f97 100644 > --- a/drivers/net/mdio/mdio-ipq4019.c > +++ b/drivers/net/mdio/mdio-ipq4019.c > @@ -188,7 +188,7 @@ static int ipq_mdio_reset(struct mii_bus *bus) > /* To indicate CMN_PLL that ethernet_ldo has been ready if platform resource 1 > * is specified in the device tree. > */ > - if (priv->eth_ldo_rdy) { > + if (!IS_ERR(priv->eth_ldo_rdy)) { > val = readl(priv->eth_ldo_rdy); > val |= BIT(0); > writel(val, priv->eth_ldo_rdy);
There is a general pattern in the kernel that optional things are set to NULL if the resource does not exist. Often there is a get_foo_optional() which will return a NULL point if the things does not exist, the thing if it does exist, or an error code if a real error happened.
So please follow this patterns. Check the return value in ipq4019_mdio_probe(). Looking at __devm_ioremap_resource() i _think_ it returns -ENOMEM if the resource does not exist? So maybe any other error is a real error, and should be reported, and -ENOMEM should result in eth_ldo_rdy set to NULL?
Andrew
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