From d314e9e80c5ea561b73584b73806c2ae9e30f503 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Wed, 23 Mar 2016 14:36:56 -0700
Subject: Input: sur40 - fix DMA on stack

During the initialisation the driver uses a buffer on the stack for DMA.
That violates the cache coherency rules. The fix is to allocate the buffer
with kmalloc().

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/sur40.c b/drivers/input/touchscreen/sur40.c
index b6c4d03..880c40b 100644
--- a/drivers/input/touchscreen/sur40.c
+++ b/drivers/input/touchscreen/sur40.c
@@ -197,28 +197,34 @@ static int sur40_command(struct sur40_state *dev,
 static int sur40_init(struct sur40_state *dev)
 {
 	int result;
-	u8 buffer[24];
+	u8 *buffer;
+
+	buffer = kmalloc(24, GFP_KERNEL);
+	if (!buffer) {
+		result = -ENOMEM;
+		goto error;
+	}
 
 	/* stupidly replay the original MS driver init sequence */
 	result = sur40_command(dev, SUR40_GET_VERSION, 0x00, buffer, 12);
 	if (result < 0)
-		return result;
+		goto error;
 
 	result = sur40_command(dev, SUR40_GET_VERSION, 0x01, buffer, 12);
 	if (result < 0)
-		return result;
+		goto error;
 
 	result = sur40_command(dev, SUR40_GET_VERSION, 0x02, buffer, 12);
 	if (result < 0)
-		return result;
+		goto error;
 
 	result = sur40_command(dev, SUR40_UNKNOWN2,    0x00, buffer, 24);
 	if (result < 0)
-		return result;
+		goto error;
 
 	result = sur40_command(dev, SUR40_UNKNOWN1,    0x00, buffer,  5);
 	if (result < 0)
-		return result;
+		goto error;
 
 	result = sur40_command(dev, SUR40_GET_VERSION, 0x03, buffer, 12);
 
@@ -226,7 +232,8 @@ static int sur40_init(struct sur40_state *dev)
 	 * Discard the result buffer - no known data inside except
 	 * some version strings, maybe extract these sometime...
 	 */
-
+error:
+	kfree(buffer);
 	return result;
 }
 
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