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

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Date:	Tue, 15 Sep 2015 15:37:58 +0100
From:	Måns Rullgård <mans@...sr.com>
To:	Michael Turquette <mturquette@...libre.com>
Cc:	Rhyland Klein <rklein@...dia.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()

Michael Turquette <mturquette@...aro.org> writes:

> 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.

Did this get lost somewhere?  It's not in mainline, and I can't find it
in the clk tree on kernel.org either.

-- 
Måns Rullgård
mans@...sr.com
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