linux-kernel - Re: [PATCH v4 09/14] of: reserved-memory: Fix using wrong number of cells to get property 'alignment'

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: <b3a103b8-7774-49c5-9d8a-04a9dae2c210@icloud.com>
Date: Thu, 27 Feb 2025 07:25:48 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: William McVicker <willmcvicker@...gle.com>, Rob Herring <robh@...nel.org>
Cc: Zijun Hu <quic_zijuhu@...cinc.com>, Saravana Kannan
 <saravanak@...gle.com>, Maxime Ripard <mripard@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Grant Likely
 <grant.likely@...retlab.ca>, Marc Zyngier <maz@...nel.org>,
 Andreas Herrmann <andreas.herrmann@...xeda.com>,
 Marek Szyprowski <m.szyprowski@...sung.com>,
 Catalin Marinas <catalin.marinas@....com>, Mike Rapoport <rppt@...nel.org>,
 Oreoluwa Babatunde <quic_obabatun@...cinc.com>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH v4 09/14] of: reserved-memory: Fix using wrong number of
 cells to get property 'alignment'

On 2025/2/27 05:36, William McVicker wrote:
>> Every time this code is touched, it breaks. This is not even the only
>> breakage right now[1].
> You can find the Pixel 6/7/8/9 device trees on android.googlesource.com.
> You can see for zuma based devices (Pixel 9 for example) they have this [1]:
> 
>   &reserved_memory {
>         #address-cells = <2>;
>         #size-cells = <1>;
>         vstream: vstream {
>                 compatible = "shared-dma-pool";
>                 reusable;
>                 size = <0x4800000>;
>                 alignment = <0x0 0x00010000>;
>                 alloc-ranges = <0x9 0x80000000 0x80000000>,
>                                <0x9 0x00000000 0x80000000>,
>                                <0x8 0x80000000 0x80000000>,
>                                <0x0 0x80000000 0x80000000>;
>         };
> 
> I understand this code is downstream, but as a general principle we shouldn't
> break backwards compatibilty.

this is not backward compatibility issue. it is a downstream bug instead.

normally, you need to write DTS according to relevant DT binding spec or
DT spec.

i can't access the link you shared due to my country's GFW.
does google kernel have extra binding spec about size of property
'alignment'?

IMO, downstream maintainers may needs to fix this issue by if the
upstream fix is picked up.
- alignment = <0x0 0x00010000>;
+ alignment = <0x00010000>;

actually, "The importance of getting code into the mainline" within
Documentation/process/1.Intro.rst encourages upstream your code to
avoid such issue.