linux-kernel - Re: [PATCH] media: mediatek: vcodec: Add scp

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Message-ID: <CANeGvZUhFV362NztbvicehGzTDWJP7uu45hT0ebmbgLTx_v-3w@mail.gmail.com>
Date: Tue, 18 Feb 2025 13:22:14 -0500
From: Jiasheng Jiang <jiashengjiangcool@...il.com>
To: Sebastian Fricke <sebastian.fricke@...labora.com>
Cc: "tiffany.lin" <tiffany.lin@...iatek.com>, 
	"andrew-ct.chen" <andrew-ct.chen@...iatek.com>, "yunfei.dong" <yunfei.dong@...iatek.com>, 
	mchehab <mchehab@...nel.org>, "matthias.bgg" <matthias.bgg@...il.com>, 
	"angelogioacchino.delregno" <angelogioacchino.delregno@...labora.com>, 
	fullwaywang <fullwaywang@...look.com>, linux-media <linux-media@...r.kernel.org>, 
	linux-kernel <linux-kernel@...r.kernel.org>, 
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, 
	linux-mediatek <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH] media: mediatek: vcodec: Add scp_put() to free the scp

Hi Sebastian,

On Fri, Feb 14, 2025 at 3:20 PM Sebastian Fricke
<sebastian.fricke@...labora.com> wrote:
>
> Hey Jiasheng,
>
>  ---- On Fri, 31 Jan 2025 02:28:30 +0100  Jiasheng Jiang <jiashengjiangcool@...il.com> wrote ---
>  > Add scp_put() to free the scp if devm_kzalloc() fails to avoid memory
>  > leak.
>
> Your commit message sounds a bit like you copy-pasted your code into the commit message.
> What kind of memory is leaking here? Are we talking about SRAM memory?
> I'd reword the commit message to something like this to give a bit more context:
>
> On Mediatek devices with a system companion processor (SCP) the mtk_scp structure has to be removed explicitly to avoid a memory leak.
> Free the structure in case the allocation of the firmware structure fails during the firmware initialization.
>
> ---
>
> Additionally, the commit title says close to nothing to the reader as well.
> How about: Fix memory leak in FW initialization
>
> But as I stated above you should clarify what kind of memory we are talking about here.
>
> Also just out of interest have you ever actually experienced issues with this?
> It seems to me that the situation where you run out of Kernel memory should be quite rare.

Yes, I just detected such a bug with a static analysis tool and I have
no idea how to trigger it.
I will submit a v2 to reword the commit message.

Thanks,
Jiasheng

>
> Regards,
> Sebastian
>
>  >
>  > Fixes: 53dbe0850444 ("media: mtk-vcodec: potential null pointer deference in SCP")
>  > Signed-off-by: Jiasheng Jiang <jiashengjiangcool@...il.com>
>  > ---
>  >  .../platform/mediatek/vcodec/common/mtk_vcodec_fw_scp.c      | 5 ++++-
>  >  1 file changed, 4 insertions(+), 1 deletion(-)
>  >
>  > diff --git a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_scp.c b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_scp.c
>  > index ff23b225db70..1b0bc47355c0 100644
>  > --- a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_scp.c
>  > +++ b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_scp.c
>  > @@ -79,8 +79,11 @@ struct mtk_vcodec_fw *mtk_vcodec_fw_scp_init(void *priv, enum mtk_vcodec_fw_use
>  >      }
>  >
>  >      fw = devm_kzalloc(&plat_dev->dev, sizeof(*fw), GFP_KERNEL);
>  > -    if (!fw)
>  > +    if (!fw) {
>  > +        scp_put(scp);
>  >          return ERR_PTR(-ENOMEM);
>  > +    }
>  > +
>  >      fw->type = SCP;
>  >      fw->ops = &mtk_vcodec_rproc_msg;
>  >      fw->scp = scp;
>  > --
>  > 2.25.1
>  >
>  >
>  >
>