eCryptfs: fix 32 bit corruption issue

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>

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index d10757635b9c9360288e18217b28de298fc48407..40db6880cdd63ba64b9805425603498898060bfc 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -408,7 +408,7 @@ static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
                                    struct page *page)
 {
        return ecryptfs_lower_header_size(crypt_stat) +
-              (page->index << PAGE_CACHE_SHIFT);
+              ((loff_t)page->index << PAGE_CACHE_SHIFT);
 }
 
 /**