linux-kernel - [PATCH 4.12 31/31] mmc: tmio-mmc: fix bad pointer math

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Date:   Thu,  3 Aug 2017 16:18:01 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Chris Brandt <chris.brandt@...esas.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: [PATCH 4.12 31/31] mmc: tmio-mmc: fix bad pointer math

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Brandt <chris.brandt@...esas.com>

commit 9c284c41c0886f09e75c323a16278b6d353b0b4a upstream.

The existing code gives an incorrect pointer value.
The buffer pointer 'buf' was of type unsigned short *, and 'count' was a
number in bytes. A cast of buf should have been used.

However, instead of casting, just change the code to use u32 pointers.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Fixes: 8185e51f358a: ("mmc: tmio-mmc: add support for 32bit data port")
Signed-off-by: Chris Brandt <chris.brandt@...esas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
Acked-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 drivers/mmc/host/tmio_mmc_pio.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -404,30 +404,29 @@ static void tmio_mmc_transfer_data(struc
 	 * Transfer the data
 	 */
 	if (host->pdata->flags & TMIO_MMC_32BIT_DATA_PORT) {
-		u8 data[4] = { };
+		u32 data = 0;
+		u32 *buf32 = (u32 *)buf;
 
 		if (is_read)
-			sd_ctrl_read32_rep(host, CTL_SD_DATA_PORT, (u32 *)buf,
+			sd_ctrl_read32_rep(host, CTL_SD_DATA_PORT, buf32,
 					   count >> 2);
 		else
-			sd_ctrl_write32_rep(host, CTL_SD_DATA_PORT, (u32 *)buf,
+			sd_ctrl_write32_rep(host, CTL_SD_DATA_PORT, buf32,
 					    count >> 2);
 
 		/* if count was multiple of 4 */
 		if (!(count & 0x3))
 			return;
 
-		buf8 = (u8 *)(buf + (count >> 2));
+		buf32 += count >> 2;
 		count %= 4;
 
 		if (is_read) {
-			sd_ctrl_read32_rep(host, CTL_SD_DATA_PORT,
-					   (u32 *)data, 1);
-			memcpy(buf8, data, count);
+			sd_ctrl_read32_rep(host, CTL_SD_DATA_PORT, &data, 1);
+			memcpy(buf32, &data, count);
 		} else {
-			memcpy(data, buf8, count);
-			sd_ctrl_write32_rep(host, CTL_SD_DATA_PORT,
-					    (u32 *)data, 1);
+			memcpy(&data, buf32, count);
+			sd_ctrl_write32_rep(host, CTL_SD_DATA_PORT, &data, 1);
 		}
 
 		return;