linux-kernel - Re: [PATCH v3 4/9] backlight: qcom-wled: Fix off-by-one maximum with default num

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20211116115853.mujwmb3v4r5s6c5v@maple.lan>
Date:   Tue, 16 Nov 2021 11:58:53 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Marijn Suijten <marijn.suijten@...ainline.org>
Cc:     phone-devel@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        ~postmarketos/upstreaming@...ts.sr.ht,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Martin Botka <martin.botka@...ainline.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        Pavel Dubrova <pashadubrova@...il.com>,
        Kiran Gunda <kgunda@...eaurora.org>,
        Bryan Wu <cooloney@...il.com>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        Courtney Cavin <courtney.cavin@...ymobile.com>
Subject: Re: [PATCH v3 4/9] backlight: qcom-wled: Fix off-by-one maximum with
 default num_strings

On Mon, Nov 15, 2021 at 09:34:54PM +0100, Marijn Suijten wrote:
> When not specifying num-strings in the DT the default is used, but +1 is
> added to it which turns WLED3 into 4 and WLED4/5 into 5 strings instead
> of 3 and 4 respectively, causing out-of-bounds reads and register
> read/writes.  This +1 exists for a deficiency in the DT parsing code,
> and is simply omitted entirely - solving this oob issue - by parsing the
> property separately much like qcom,enabled-strings.
> 
> This also enables more stringent checks on the maximum value when
> qcom,enabled-strings is provided in the DT, by parsing num-strings after
> enabled-strings to allow it to check against (and in a subsequent patch
> override) the length of enabled-strings: it is invalid to set
> num-strings higher than that.
> The DT currently utilizes it to get around an incorrect fixed read of
> four elements from that array (has been addressed in a prior patch) by
> setting a lower num-strings where desired.
> 
> Fixes: 93c64f1ea1e8 ("leds: add Qualcomm PM8941 WLED driver")
> Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
> Reviewed-By: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>

Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>


Daniel.