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From:   Hsin-Yi Wang <hsinyi@chromium.org>
To:     Robert Foss <robert.foss@linaro.org>,
        David Airlie <airlied@linux.ie>,
        Allen Chen <allen.chen@ite.com.tw>
Cc:     Neil Armstrong <narmstrong@baylibre.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Hermes Wu <hermes.wu@ite.com.tw>,
        Daniel Vetter <daniel@ffwll.ch>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH] drm/bridge: it6505: Fix the read buffer array bound
Date:   Mon, 28 Feb 2022 16:14:21 +0800
Message-Id: <20220228081421.1504213-1-hsinyi@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The size of read_buf is READ_BUFFER_SIZE (200), so we can't access it
with read_buf + PAGE_SIZE (4096). Extend the READ_BUFFER_SIZE to 400 and
set the end position to read_buf + READ_BUFFER_SIZE.

Fixes: b5c84a9edcd418 ("drm/bridge: add it6505 driver")
Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index fb16a176822d81..f2f101220ade94 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -289,7 +289,7 @@
 #define WORD_LENGTH_20BIT 2
 #define WORD_LENGTH_24BIT 3
 #define DEBUGFS_DIR_NAME "it6505-debugfs"
-#define READ_BUFFER_SIZE 200
+#define READ_BUFFER_SIZE 400
 
 /* Vendor option */
 #define HDCP_DESIRED 1
@@ -3074,7 +3074,7 @@ static ssize_t receive_timing_debugfs_show(struct file *file, char __user *buf,
 	struct it6505 *it6505 = file->private_data;
 	struct drm_display_mode *vid = &it6505->video_info;
 	u8 read_buf[READ_BUFFER_SIZE];
-	u8 *str = read_buf, *end = read_buf + PAGE_SIZE;
+	u8 *str = read_buf, *end = read_buf + READ_BUFFER_SIZE;
 	ssize_t ret, count;
 
 	if (!it6505)
-- 
2.35.1.574.g5d30c73bfb-goog