Re: [PATCH] clk: check for invalid parent index of orphans in __clk_init()

[Rhyland Klein]

On 2/15/2015 7:33 AM, Mans Rullgard wrote:
> If a mux clock is initialised (by hardware or firmware) with an
> invalid parent, its ->get_parent() can return an out of range
> index.  For example, the generic mux clock attempts to return
> -EINVAL, which due to the u8 return type ends up a rather large
> number.  Using this index with the parent_names[] array results
> in an invalid pointer and (usually) a crash in the following
> strcmp().
> 
> This patch adds a check for the parent index being in range,
> ignoring clocks reporting invalid values.
> 
> Signed-off-by: Mans Rullgard <mans@xxxxxxxxx>
> Cc: Rhyland Klein <rklein@xxxxxxxxxx>
> ---
>  drivers/clk/clk.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index d48ac71..bc0662b 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1950,7 +1950,8 @@ int __clk_init(struct device *dev, struct clk *clk)
>  	hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
>  		if (orphan->num_parents && orphan->ops->get_parent) {
>  			i = orphan->ops->get_parent(orphan->hw);
> -			if (!strcmp(clk->name, orphan->parent_names[i]))
> +			if (i >= 0 && i < orphan->num_parents &&
> +			    !strcmp(clk->name, orphan->parent_names[i]))
>  				__clk_reparent(orphan, clk);
>  			continue;
>  		}
> 

This works for me and is less invasive than the original patch series.

Tested-by: Rhyland Klein <rklein@xxxxxxxxxx>

-rhyland

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