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Message-ID: <20250904103443.GH372207@horms.kernel.org>
Date: Thu, 4 Sep 2025 11:34:43 +0100
From: Simon Horman <horms@...nel.org>
To: Yao Zi <ziyao@...root.org>
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
Jonas Karlman <jonas@...boo.se>, David Wu <david.wu@...k-chips.com>,
Chaoyi Chen <chaoyi.chen@...k-chips.com>, netdev@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH net] net: stmmac: dwmac-rk: Ensure clk_phy doesn't
contain invalid address
On Thu, Sep 04, 2025 at 03:12:24AM +0000, Yao Zi wrote:
> We must set the clk_phy pointer to NULL to indicating it isn't available
> if the optional phy clock couldn't be obtained. Otherwise the error code
> returned by of_clk_get() could be wrongly taken as an address, causing
> invalid pointer dereference when later clk_phy is passed to
> clk_prepare_enable().
>
> Fixes: da114122b831 ("net: ethernet: stmmac: dwmac-rk: Make the clk_phy could be used for external phy")
> Signed-off-by: Yao Zi <ziyao@...root.org>
> ---
> drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> On next-20250903, the fixed commit causes NULL pointer dereference on
> Radxa E20C during probe of dwmac-rk, a typical dmesg looks like
>
> [ 0.273324] rk_gmac-dwmac ffbe0000.ethernet: IRQ eth_lpi not found
> [ 0.273888] rk_gmac-dwmac ffbe0000.ethernet: IRQ sfty not found
> [ 0.274520] rk_gmac-dwmac ffbe0000.ethernet: PTP uses main clock
> [ 0.275226] rk_gmac-dwmac ffbe0000.ethernet: clock input or output? (output).
> [ 0.275867] rk_gmac-dwmac ffbe0000.ethernet: Can not read property: tx_delay.
> [ 0.276491] rk_gmac-dwmac ffbe0000.ethernet: set tx_delay to 0x30
> [ 0.277026] rk_gmac-dwmac ffbe0000.ethernet: Can not read property: rx_delay.
> [ 0.278086] rk_gmac-dwmac ffbe0000.ethernet: set rx_delay to 0x10
> [ 0.278658] rk_gmac-dwmac ffbe0000.ethernet: integrated PHY? (no).
> [ 0.279249] Unable to handle kernel paging request at virtual address fffffffffffffffe
> [ 0.279948] Mem abort info:
> [ 0.280195] ESR = 0x000000096000006
> [ 0.280523] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 0.280989] SET = 0, FnV = 0
> [ 0.281287] EA = 0, S1PTW = 0
> [ 0.281574] FSC = 0x06: level 2 translation fault
>
> where the invalid address is just -ENOENT (-2).
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> index cf619a428664..26ec8ae662a6 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> @@ -1414,11 +1414,17 @@ static int rk_gmac_clk_init(struct plat_stmmacenet_data *plat)
> if (plat->phy_node) {
> bsp_priv->clk_phy = of_clk_get(plat->phy_node, 0);
> ret = PTR_ERR_OR_ZERO(bsp_priv->clk_phy);
> - /* If it is not integrated_phy, clk_phy is optional */
> + /*
> + * If it is not integrated_phy, clk_phy is optional. But we must
> + * set bsp_priv->clk_phy to NULL if clk_phy isn't proivded, or
> + * the error code could be wrongly taken as an invalid pointer.
> + */
> if (bsp_priv->integrated_phy) {
> if (ret)
> return dev_err_probe(dev, ret, "Cannot get PHY clock\n");
> clk_set_rate(bsp_priv->clk_phy, 50000000);
> + } else if (ret) {
> + bsp_priv->clk_phy = NULL;
> }
> }
Thanks, and sorry for my early confusion about applying this patch.
I agree that the bug you point out is addressed by this patch.
Although I wonder if it is cleaner not to set bsp_priv->clk_phy
unless there is no error, rather than setting it then resetting
it if there is an error.
More importantly, I wonder if there is another bug: does clk_set_rate need
to be called in the case where there is no error and bsp_priv->integrated_phy
is false?
So I am wondering if it makes sense to go with something like this.
(Compile tested only!)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
index 266c53379236..a25816af2c37 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
@@ -1411,12 +1411,16 @@ static int rk_gmac_clk_init(struct plat_stmmacenet_data *plat)
}
if (plat->phy_node) {
- bsp_priv->clk_phy = of_clk_get(plat->phy_node, 0);
- ret = PTR_ERR_OR_ZERO(bsp_priv->clk_phy);
- /* If it is not integrated_phy, clk_phy is optional */
- if (bsp_priv->integrated_phy) {
- if (ret)
+ struct clk *clk_phy;
+
+ clk_phy = of_clk_get(plat->phy_node, 0);
+ ret = PTR_ERR_OR_ZERO(clk_phy);
+ if (ret) {
+ /* If it is not integrated_phy, clk_phy is optional */
+ if (bsp_priv->integrated_phy)
return dev_err_probe(dev, ret, "Cannot get PHY clock\n");
+ } else {
+ bsp_priv->clk_phy = clk_phy;
clk_set_rate(bsp_priv->clk_phy, 50000000);
}
}
Please note: if you send an updated patch (against net) please
make sure you wait 24h before the original post.
See: https://docs.kernel.org/process/maintainer-netdev.html
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