linux-kernel - Re: [PATCH RESEND] drm/mediatek/dp: fix spurious kfree()

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Date: Fri, 28 Jun 2024 21:08:40 +0800
From: Chun-Kuang Hu <chunkuang.hu@...nel.org>
To: Michael Walle <mwalle@...nel.org>
Cc: Chun-Kuang Hu <chunkuang.hu@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Matthias Brugger <matthias.bgg@...il.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Jani Nikula <jani.nikula@...el.com>, Chen-Yu Tsai <wenst@...omium.org>, 
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RESEND] drm/mediatek/dp: fix spurious kfree()

Hi, Michael:

Michael Walle <mwalle@...nel.org> 於 2024年6月4日 週二 下午4:33寫道：
>
> drm_edid_to_sad() might return an error or just zero. If that is the
> case, we must not free the SADs because there was no allocation in
> the first place.

Applied to mediatek-drm-next [1], thanks.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next

>
> Fixes: dab12fa8d2bd ("drm/mediatek/dp: fix memory leak on ->get_edid callback audio detection")
> Signed-off-by: Michael Walle <mwalle@...nel.org>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> Reviewed-by: Jani Nikula <jani.nikula@...el.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 536366956447..ada12927bbac 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -2073,9 +2073,15 @@ static const struct drm_edid *mtk_dp_edid_read(struct drm_bridge *bridge,
>                  */
>                 const struct edid *edid = drm_edid_raw(drm_edid);
>                 struct cea_sad *sads;
> +               int ret;
>
> -               audio_caps->sad_count = drm_edid_to_sad(edid, &sads);
> -               kfree(sads);
> +               ret = drm_edid_to_sad(edid, &sads);
> +               /* Ignore any errors */
> +               if (ret < 0)
> +                       ret = 0;
> +               if (ret)
> +                       kfree(sads);
> +               audio_caps->sad_count = ret;
>
>                 /*
>                  * FIXME: This should use connector->display_info.has_audio from
> --
> 2.39.2
>