[PATCH 3.11 34/94] eCryptfs: fix 32 bit corruption issue

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Colin Ian King <colin.king@canonical.com>

commit 43b7c6c6a4e3916edd186ceb61be0c67d1e0969e upstream.

Shifting page->index on 32 bit systems was overflowing, causing
data corruption of > 4GB files. Fix this by casting it first.

https://launchpad.net/bugs/1243636

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reported-by: Lars Duesing <lars.duesing@camelotsweb.de>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ecryptfs/crypto.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -408,7 +408,7 @@ static loff_t lower_offset_for_page(stru
 				    struct page *page)
 {
 	return ecryptfs_lower_header_size(crypt_stat) +
-	       (page->index << PAGE_CACHE_SHIFT);
+	       ((loff_t)page->index << PAGE_CACHE_SHIFT);
 }
 
 /**