linux-kernel - [PATCH] nfsd: fix bad offset use

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Date:	Fri, 22 Mar 2013 11:18:24 -0700
From:	Kent Overstreet <koverstreet@...gle.com>
To:	linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org
Cc:	Kent Overstreet <koverstreet@...gle.com>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Zach Brown <zab@...hat.com>
Subject: [PATCH] nfsd: fix bad offset use

vfs_writev() updates the offset argument - but the code then passes the
offset to vfs_fsync_range(). Since offset now points to the offset after
what was just written, this is probably not what was intended

Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
Cc: "J. Bruce Fields" <bfields@...ldses.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Zach Brown <zab@...hat.com>
---
 fs/nfsd/vfs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 2a7eb53..2b2e239 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1013,6 +1013,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 	int			host_err;
 	int			stable = *stablep;
 	int			use_wgather;
+	loff_t			pos = offset;
 
 	dentry = file->f_path.dentry;
 	inode = dentry->d_inode;
@@ -1025,7 +1026,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 
 	/* Write the data. */
 	oldfs = get_fs(); set_fs(KERNEL_DS);
-	host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &offset);
+	host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &pos);
 	set_fs(oldfs);
 	if (host_err < 0)
 		goto out_nfserr;
-- 
1.8.1.3

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