eCryptfs: fix 32 bit corruption issue

Colin Ian King · tyhicks · commit 43b7c6c6a4e3 · 2013-10-24T12:36:30.000-07:00
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> Cc: stable@vger.kernel.org # v3.11+ Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
diff --git 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);
 }
 
 /**

Original file line number	Diff line number	Diff line change
`@@ -408,7 +408,7 @@ static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,`
`408`	`408`	`struct page *page)`
`409`	`409`	`{`
`410`	`410`	`return ecryptfs_lower_header_size(crypt_stat) +`
`411`		`- (page->index << PAGE_CACHE_SHIFT);`
	`411`	`+ ((loff_t)page->index << PAGE_CACHE_SHIFT);`
`412`	`412`	`}`
`413`	`413`
`414`	`414`	`/**`