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

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Message-Id: <20240604083337.1879188-1-mwalle@kernel.org>
Date: Tue,  4 Jun 2024 10:33:37 +0200
From: Michael Walle <mwalle@...nel.org>
To: 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>
Cc: 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,
	Michael Walle <mwalle@...nel.org>
Subject: [PATCH RESEND] drm/mediatek/dp: fix spurious kfree()

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.

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