linux-kernel - [PATCH 4.19 08/78] drm/sun4i: Fix dsi dcs long write function

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Date:   Tue, 15 Sep 2020 16:12:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ondrej Jirman <megous@...ous.com>,
        Maxime Ripard <maxime@...no.tech>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 08/78] drm/sun4i: Fix dsi dcs long write function

From: Ondrej Jirman <megous@...ous.com>

[ Upstream commit fd90e3808fd2c207560270c39b86b71af2231aa1 ]

It's writing too much data. regmap_bulk_write expects number of
register sized chunks to write, not a byte sized length of the
bounce buffer. Bounce buffer needs to be padded too, so that
regmap_bulk_write will not read past the end of the buffer.

Fixes: 133add5b5ad4 ("drm/sun4i: Add Allwinner A31 MIPI-DSI controller support")
Signed-off-by: Ondrej Jirman <megous@...ous.com>
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Reviewed-by: Jernej Skrabec <jernej.skrabec@...l.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200828125032.937148-1-megous@megous.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 79eb11cd185d1..9a5584efd5e78 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -761,7 +761,7 @@ static int sun6i_dsi_dcs_write_long(struct sun6i_dsi *dsi,
 	regmap_write(dsi->regs, SUN6I_DSI_CMD_TX_REG(0),
 		     sun6i_dsi_dcs_build_pkt_hdr(dsi, msg));
 
-	bounce = kzalloc(msg->tx_len + sizeof(crc), GFP_KERNEL);
+	bounce = kzalloc(ALIGN(msg->tx_len + sizeof(crc), 4), GFP_KERNEL);
 	if (!bounce)
 		return -ENOMEM;
 
@@ -772,7 +772,7 @@ static int sun6i_dsi_dcs_write_long(struct sun6i_dsi *dsi,
 	memcpy((u8 *)bounce + msg->tx_len, &crc, sizeof(crc));
 	len += sizeof(crc);
 
-	regmap_bulk_write(dsi->regs, SUN6I_DSI_CMD_TX_REG(1), bounce, len);
+	regmap_bulk_write(dsi->regs, SUN6I_DSI_CMD_TX_REG(1), bounce, DIV_ROUND_UP(len, 4));
 	regmap_write(dsi->regs, SUN6I_DSI_CMD_CTL_REG, len + 4 - 1);
 	kfree(bounce);
 
-- 
2.25.1