linux-kernel - [PATCH 3.12 062/235] nfs_write_end(): fix handling of short copies

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Message-Id: <274125f9db7a9bad1ffdbad5e84f4f1a5566ca42.1485514374.git.jslaby@suse.cz>
Date:   Fri, 27 Jan 2017 11:53:15 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 062/235] nfs_write_end(): fix handling of short copies

From: Al Viro <viro@...iv.linux.org.uk>

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

===============

commit c0cf3ef5e0f47e385920450b245d22bead93e7ad upstream.

What matters when deciding if we should make a page uptodate is
not how much we _wanted_ to copy, but how much we actually have
copied.  As it is, on architectures that do not zero tail on
short copy we can leave uninitialized data in page marked uptodate.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 fs/nfs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 1e6bfdbc1aff..0a0b5063e50e 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -425,7 +425,7 @@ static int nfs_write_end(struct file *file, struct address_space *mapping,
 	 */
 	if (!PageUptodate(page)) {
 		unsigned pglen = nfs_page_length(page);
-		unsigned end = offset + len;
+		unsigned end = offset + copied;
 
 		if (pglen == 0) {
 			zero_user_segments(page, 0, offset,
-- 
2.11.0