Re: [PATCH v3 5/5] phy: qcom: snps-femto-v2: Fix possible NULL-deref on early runtime suspend

From: Johan Hovold <johan@kernel.org>
To: Loic Poulain <loic.poulain@oss.qualcomm.com>
Cc: vkoul@kernel.org, kishon@kernel.org,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	dmitry.baryshkov@oss.qualcomm.com, neil.armstrong@linaro.org,
	konrad.dybcio@oss.qualcomm.com,
	Abel Vesa <abel.vesa@oss.qualcomm.com>
Subject: Re: [PATCH v3 5/5] phy: qcom: snps-femto-v2: Fix possible NULL-deref on early runtime suspend
Date: Fri, 13 Feb 2026 10:07:09 +0100	[thread overview]
Message-ID: <aY7pvakkOnaYsd5p@hovoldconsulting.com> (raw)
In-Reply-To: <20260205160240.748371-6-loic.poulain@oss.qualcomm.com>

On Thu, Feb 05, 2026 at 05:02:40PM +0100, Loic Poulain wrote:
> Enabling runtime PM before attaching the hsphy instance as driver data
> can lead to a NULL pointer dereference in runtime PM callbacks that
> expect valid driver data. There is a small window where the suspend
> callback may run after PM runtime enabling and before runtime forbid.

So here too, the commit should reflect that this cannot really happen in
practice.

> Attach the hsphy instance as driver data before enabling runtime PM to
> prevent NULL pointer dereference in runtime PM callbacks.
> 
> Reorder pm_runtime_enable() and pm_runtime_forbid() to prevent a
> short window where an unnecessary runtime suspend can occur.
> 
> Use the devres-managed version to ensure PM runtime is symmetrically
> disabled during driver removal for proper cleanup.
> 
> Fixes: 0d75f508a9d5 ("phy: qcom-snps: Add runtime suspend and resume handlers")
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
> Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>

Johan