linux-kernel - Re: [PATCH 1/2] OPP: add index check to assert to avoid buffer overflow in _read

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Message-ID: <c6b5b6f7-ab55-4d46-888e-f9e00b269c9c@linaro.org>
Date: Fri, 29 Nov 2024 09:53:45 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
 Stephen Boyd <sboyd@...nel.org>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] OPP: add index check to assert to avoid buffer
 overflow in _read_freq()

Hi,

On 29/11/2024 09:40, Viresh Kumar wrote:
> On 28-11-24, 11:07, Neil Armstrong wrote:
>> Pass the freq index to the assert function to make sure
>> we do not read a freq out of the opp->rates[] table.
>>
>> Without that the index value is never checked when called from
>> dev_pm_opp_find_freq_exact_indexed() or
>> dev_pm_opp_find_freq_ceil/floor_indexed().
> 
> These APIs aren't supported for cases where we have more than one clks
> available and hence assert for single clk.
> 

I don't understand, the _indexed functions clearly have an index parameter
which is documented as "Clock index"

I agree we could leave the other ones with assert_single_clk, but we would
need to duplicate it to have one with the index parameter, so it felt simpler
to use assert_clk_index everywhere but indeed we do not exclude them for
when there's multiple clock...

Neil