releases/3.17.5/spi-fix-mapping-from-vmalloc-ed-buffer-to-scatter-list.patch

From c1aefbdd050e1fb15e92bcaf34d95b17ea952097 Mon Sep 17 00:00:00 2001
From: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Date: Mon, 17 Nov 2014 09:14:31 +0000
Subject: spi: Fix mapping from vmalloc-ed buffer to scatter list

From: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>

commit c1aefbdd050e1fb15e92bcaf34d95b17ea952097 upstream.

We can only use page_address on memory that has been mapped using kmap,
when the buffer passed to the SPI has been allocated by vmalloc the page
has not necessarily been mapped through kmap. This means sometimes
page_address will return NULL causing the pointer we pass to sg_set_buf
to be invalid.

As we only call page_address so that we can pass a virtual address to
sg_set_buf which will then immediately call virt_to_page on it, fix this
by calling sg_set_page directly rather then relying on the sg_set_buf
helper.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -609,13 +609,13 @@ static int spi_map_buf(struct spi_master
 				sg_free_table(sgt);
 				return -ENOMEM;
 			}
-			sg_buf = page_address(vm_page) +
-				((size_t)buf & ~PAGE_MASK);
+			sg_set_page(&sgt->sgl[i], vm_page,
+				    min, offset_in_page(buf));
 		} else {
 			sg_buf = buf;
+			sg_set_buf(&sgt->sgl[i], sg_buf, min);
 		}
 
-		sg_set_buf(&sgt->sgl[i], sg_buf, min);
 
 		buf += min;
 		len -= min;