Re: [PATCH 1/3] soc: mediatek: mtk-socinfo: Clean up NVMEM cell read

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
To: Chen-Yu Tsai <wenst@chromium.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	William-tw Lin <william-tw.lin@mediatek.com>
Subject: Re: [PATCH 1/3] soc: mediatek: mtk-socinfo: Clean up NVMEM cell read
Date: Tue, 30 Jan 2024 12:20:47 +0100	[thread overview]
Message-ID: <068e98bb-c4c3-4c50-83b3-a6c999abc1ff@collabora.com> (raw)
In-Reply-To: <20240130095656.3712469-2-wenst@chromium.org>

Il 30/01/24 10:56, Chen-Yu Tsai ha scritto:
> The mtk-socinfo grabs the NVMEM device devm_nvmem_device_get(), but then
> proceeds to put the device directly with nvmem_device_put() if the read
> is successful. If the device fails to probe and goes through the devres
> release path, the device would be put a second time, triggering a
> use-after-free error from KASAN.
> 
> Fix this by dropping the devres part. Since the NVMEM cell data is read
> only once, there is no need to keep the reference around.
> 
> While at it, clean up the function to directly reference the NVMEM
> device node and use that to find the NVMEM device, instead of finding it
> by name, which is more fragile. The cell node is always a direct child
> of the NVMEM device node, courtesy of the legacy NVMEM cell layout. Thus
> of_get_child_by_name() is a better way of finding the cell. Last,
> correctly put the device node once its use is over.
> 
> Fixes: 423a54da3c7e ("soc: mediatek: mtk-socinfo: Add driver for getting chip information")
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>