linux-kernel - [PATCH v1 1/1] drm/mediatek: Fix wrong check of nvmem_cell

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Message-ID: <20240925084116.28848-1-liankun.yang@mediatek.com>
Date: Wed, 25 Sep 2024 16:40:24 +0800
From: Liankun Yang <liankun.yang@...iatek.com>
To: <chunkuang.hu@...nel.org>, <p.zabel@...gutronix.de>, <airlied@...il.com>,
	<simona@...ll.ch>, <matthias.bgg@...il.com>,
	<angelogioacchino.delregno@...labora.com>, <rex-bc.chen@...iatek.com>,
	<msp@...libre.com>, <granquet@...libre.com>, <dmitry.osipenko@...labora.com>,
	<jitao.shi@...iatek.com>, <mac.shen@...iatek.com>, <peng.liu@...iatek.com>,
	<liankun.yang@...iatek.com>
CC: <Project_Global_Chrome_Upstream_Group@...iatek.com>,
	<dri-devel@...ts.freedesktop.org>, <linux-mediatek@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH v1 1/1] drm/mediatek: Fix wrong check of nvmem_cell_read

If the len is 0, kernel crash will occur when performing operations.
Add the len check conditions to prevent kernel crash.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")

Signed-off-by: Liankun Yang <liankun.yang@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index d8796a904eca..0cc75ba96b98 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1082,7 +1082,7 @@ static void mtk_dp_get_calibration_data(struct mtk_dp *mtk_dp)
 	buf = (u32 *)nvmem_cell_read(cell, &len);
 	nvmem_cell_put(cell);
 
-	if (IS_ERR(buf) || ((len / sizeof(u32)) != 4)) {
+	if (IS_ERR(buf) || (len == 0) || ((len / sizeof(u32)) != 4)) {
 		dev_warn(dev, "Failed to read nvmem_cell_read\n");
 
 		if (!IS_ERR(buf))
-- 
2.45.2