Re: [PATCH] clk: composite: fix NULL dereference when the parent clock is not set

[Jerome Brunet]

> clk_composite_determine_rate() reads the parent clock with
> clk_hw_get_parent() and hands it to
> clk_composite_determine_rate_for_parent() without checking it.
> clk_hw_get_parent() returns NULL when the clock has no parent yet, for
> example while the parent is still an orphan, and the helper dereferences
> that NULL pointer in clk_hw_get_rate(), which reads parent_hw->core and
> oopses the kernel.
> 
> Return -EINVAL when the parent clock is NULL.
> 
> Fixes: 2f508a955a67 ("clk: Convert basic types to clk_hw based provider APIs")
> Assisted-by: DeepSeek-V4.1-Flash
> Signed-off-by: Haotian Zhang <vulab@xxxxxxxxxxx>
> ---
>  drivers/clk/clk-composite.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
> index 11842bce5918..40d64ef2d325 100644
> --- a/drivers/clk/clk-composite.c
> +++ b/drivers/clk/clk-composite.c
> @@ -75,6 +75,8 @@ static int clk_composite_determine_rate(struct clk_hw *hw,
>  			struct clk_rate_request tmp_req;
>  
>  			parent = clk_hw_get_parent(mux_hw);
> +			if (!parent)
> +				return -EINVAL;

The mux return 0 on orphaned mux, so I don't think returning an error here would be wise.
Considering Krzysztof message, I'll wait a but without a clear answer from
you, I'll probably followup mentioning this message as Reported-by.

-- 
Jerome