linux-kernel - Re: [PATCH] clk: check for invalid parent index of orphans in __clk

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Date:	Mon, 13 Apr 2015 12:12:50 -0700
From:	Michael Turquette <mturquette@...aro.org>
To:	Rhyland Klein <rklein@...dia.com>,
	"Mans Rullgard" <mans@...sr.com>,
	"Stephen Boyd" <sboyd@...eaurora.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: check for invalid parent index of orphans in __clk_init()

Quoting Rhyland Klein (2015-02-17 08:58:29)
> 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@...sr.com>
> > Cc: Rhyland Klein <rklein@...dia.com>
> > ---
> >  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@...dia.com>

Applied.

Thanks,
Mike

> 
> -rhyland
> 
> -- 
> nvpublic
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