linux-kernel - Re: [PATCH v2 2/4] firmware: qcom: uefisecapp: add support for R/O UEFI vars

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Message-ID: <55624c7d-0192-43ec-b367-f33c96866a2a@oss.qualcomm.com>
Date: Mon, 23 Jun 2025 16:52:58 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Johan Hovold <johan@...nel.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/4] firmware: qcom: uefisecapp: add support for R/O
 UEFI vars

On 6/23/25 4:52 PM, Johan Hovold wrote:
> On Mon, Jun 23, 2025 at 04:49:22PM +0200, Konrad Dybcio wrote:
>> On 6/23/25 4:45 PM, Johan Hovold wrote:
> 
>>> It looks like the efivars implementation does not support read-only
>>> efivars and this will lead to NULL pointer dereferences whenever you try
>>> to write a variable.
>>
>> There's efivar_supports_writes() that is used to set the EFIVAR_OPS_RDONLY
>> flag which then sets SB_RDONLY on all efivarfs superblocks
> 
> Yep, but it doesn't help when attempting to store the RTC offset from
> the kernel (since that does not use efivarfs).

You're right, that hole needs patching

Konrad