[ 3.5.y.z extended stable ] Patch "NFSv4: Fix the string length returned by the idmapper" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Mon Apr 1 15:04:45 UTC 2013

This is a note to let you know that I have just added a patch titled

    NFSv4: Fix the string length returned by the idmapper

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 905c8646bdfebf576494649c0babeff8c8ed9702 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust at netapp.com>
Date: Fri, 8 Mar 2013 12:56:37 -0500
Subject: [PATCH] NFSv4: Fix the string length returned by the idmapper

commit cf4ab538f1516606d3ae730dce15d6f33d96b7e1 upstream.

Functions like nfs_map_uid_to_name() and nfs_map_gid_to_group() are
expected to return a string without any terminating NUL character.
Regression introduced by commit 57e62324e469e092ecc6c94a7a86fe4bd6ac5172
(NFS: Store the legacy idmapper result in the keyring).

Reported-by: Dave Chiluk <dave.chiluk at canonical.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust at netapp.com>
Cc: Bryan Schumaker <bjschuma at netapp.com>
[ luis: backported to 3.5: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 fs/nfs/idmap.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index a0972e9..e4476dc 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -710,9 +710,9 @@ out1:
 	return ret;

-static int nfs_idmap_instantiate(struct key *key, struct key *authkey, char *data)
+static int nfs_idmap_instantiate(struct key *key, struct key *authkey, char *data, size_t datalen)
-	return key_instantiate_and_link(key, data, strlen(data) + 1,
+	return key_instantiate_and_link(key, data, datalen,
@@ -720,15 +720,18 @@ static int nfs_idmap_instantiate(struct key *key, struct key *authkey, char *dat
 static int nfs_idmap_read_message(struct idmap_msg *im, struct key *key, struct key *authkey)
 	char id_str[NFS_UINT_MAXLEN];
+	size_t len;
 	int ret = -EINVAL;

 	switch (im->im_conv) {
-		sprintf(id_str, "%d", im->im_id);
-		ret = nfs_idmap_instantiate(key, authkey, id_str);
+		/* Note: here we store the NUL terminator too */
+		len = sprintf(id_str, "%d", im->im_id) + 1;
+		ret = nfs_idmap_instantiate(key, authkey, id_str, len);
-		ret = nfs_idmap_instantiate(key, authkey, im->im_name);
+		len = strlen(im->im_name);
+		ret = nfs_idmap_instantiate(key, authkey, im->im_name, len);


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