linux-kernel - [PATCH v2 07/26] drm/rockchip: dw-mipi-dsi: avoid out-of-bounds read on tx

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Message-Id: <20170121163128.22240-8-john@metanate.com>
Date:   Sat, 21 Jan 2017 16:31:09 +0000
From:   John Keeping <john@...anate.com>
To:     Mark Yao <mark.yao@...k-chips.com>
Cc:     Chris Zhong <zyw@...k-chips.com>, dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        John Keeping <john@...anate.com>
Subject: [PATCH v2 07/26] drm/rockchip: dw-mipi-dsi: avoid out-of-bounds read on tx_buf

As a side-effect of this, encode the endianness explicitly rather than
casting a u16.

Signed-off-by: John Keeping <john@...anate.com>
---
Unchanged in v2
---
 drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
index 4be1ff3a42bb..2e6ad4591ebf 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
@@ -572,8 +572,13 @@ static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 hdr_val)
 static int dw_mipi_dsi_dcs_short_write(struct dw_mipi_dsi *dsi,
 				       const struct mipi_dsi_msg *msg)
 {
-	const u16 *tx_buf = msg->tx_buf;
-	u32 val = GEN_HDATA(*tx_buf) | GEN_HTYPE(msg->type);
+	const u8 *tx_buf = msg->tx_buf;
+	u32 val = GEN_HTYPE(msg->type);
+
+	if (msg->tx_len > 0)
+		val |= GEN_HDATA(tx_buf[0]);
+	if (msg->tx_len > 1)
+		val |= GEN_HDATA(tx_buf[1] << 8);
 
 	if (msg->tx_len > 2) {
 		dev_err(dsi->dev, "too long tx buf length %zu for short write\n",
-- 
2.11.0.197.gb556de5.dirty