linux-kernel - [PATCH 3.2 037/152] nfs: don't create zero-length requests

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1479082447.644169869@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:07 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Alexey Dobriyan" <adobriyan@...il.com>,
        "Benjamin Coddington" <bcodding@...hat.com>,
        "Trond Myklebust" <trond.myklebust@...marydata.com>,
        "Weston Andros Adamson" <dros@...marydata.com>
Subject: [PATCH 3.2 037/152] nfs: don't create zero-length requests

3.2.84-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Benjamin Coddington <bcodding@...hat.com>

commit 149a4fddd0a72d526abbeac0c8deaab03559836a upstream.

NFS doesn't expect requests with wb_bytes set to zero and may make
unexpected decisions about how to handle that request at the page IO layer.
Skip request creation if we won't have any wb_bytes in the request.

Signed-off-by: Benjamin Coddington <bcodding@...hat.com>
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
Reviewed-by: Weston Andros Adamson <dros@...marydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@...marydata.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/nfs/write.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -747,6 +747,9 @@ int nfs_updatepage(struct file *file, st
 		file->f_path.dentry->d_name.name, count,
 		(long long)(page_offset(page) + offset));
 
+	if (!count)
+		goto out;
+
 	/* If we're not using byte range locks, and we know the page
 	 * is up to date, it may be more efficient to extend the write
 	 * to cover the entire page in order to avoid fragmentation
@@ -764,7 +767,7 @@ int nfs_updatepage(struct file *file, st
 		nfs_set_pageerror(page);
 	else
 		__set_page_dirty_nobuffers(page);
-
+out:
 	dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 			status, (long long)i_size_read(inode));
 	return status;