[PATCH] [Quantal][SRU] (upstream) NFSv4: Fix the string length returned by the idmapper

[Dave Chiluk]

BugLink: http://bugs.launchpad.net/bugs/1101292

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).

This fixes inability to chown or chgrp files on AIX nfs shares.

Reported-by: Dave Chiluk <chiluk at canonical.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust at netapp.com>
Cc: Bryan Schumaker <bjschuma at netapp.com>
Cc: stable at vger.kernel.org [>=3.4]
(backported from commit 3070d4a2f8aa4ac06f424eb497637d41d049bb3a linux)

Signed-off-by: Dave Chiluk <chiluk at canonical.com>
---
 fs/nfs/idmap.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
 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,
 					id_resolver_cache->thread_keyring,
 					authkey);
 }
@@ -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) {
 	case IDMAP_CONV_NAMETOID:
-		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);
 		break;
 	case IDMAP_CONV_IDTONAME:
-		ret = nfs_idmap_instantiate(key, authkey, im->im_name);
+		len = strlen(im->im_name);
+		ret = nfs_idmap_instantiate(key, authkey, im->im_name, len);
 		break;
 	}
 
-- 
1.7.9.5