This is a note to let you know that I've just added the patch titled
nfs: don't zero out the rest of the page if we hit the EOF on a DIO READ
to the 3.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfs-don-t-zero-out-the-rest-of-the-page-if-we-hit-the-eof-on-a-dio-read.patch
and it can be found in the queue-3.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 67fad106a219e083c91c79695bd1807dde1bf7b9 Mon Sep 17 00:00:00 2001
From: Jeff Layton <[email protected]>
Date: Wed, 12 Dec 2012 11:38:44 -0500
Subject: nfs: don't zero out the rest of the page if we hit the EOF on a DIO
READ
From: Jeff Layton <[email protected]>
commit 67fad106a219e083c91c79695bd1807dde1bf7b9 upstream.
Eryu provided a test program that would segfault when attempting to read
past the EOF on file that was opened O_DIRECT. The buffer given to the
read() call was on the stack, and when he attempted to read past it it
would scribble over the rest of the stack page.
If we hit the end of the file on a DIO READ request, then we don't want
to zero out the rest of the buffer. These aren't pagecache pages after
all, and there's no guarantee that the buffers that were passed in
represent entire pages.
Reported-by: Eryu Guan <[email protected]>
Cc: Fred Isaman <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/nfs/direct.c | 8 --------
1 file changed, 8 deletions(-)
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -266,14 +266,6 @@ static void nfs_direct_read_completion(s
struct nfs_page *req = nfs_list_entry(hdr->pages.next);
struct page *page = req->wb_page;
- if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
- if (bytes > hdr->good_bytes)
- zero_user(page, 0, PAGE_SIZE);
- else if (hdr->good_bytes - bytes < PAGE_SIZE)
- zero_user_segment(page,
- hdr->good_bytes & ~PAGE_MASK,
- PAGE_SIZE);
- }
if (!PageCompound(page)) {
if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
if (bytes < hdr->good_bytes)
Patches currently in stable-queue which might be from [email protected] are
queue-3.7/nfs-don-t-extend-writes-to-cover-entire-page-if-pagecache-is-invalid.patch
queue-3.7/nfs-don-t-zero-out-the-rest-of-the-page-if-we-hit-the-eof-on-a-dio-read.patch
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