cifs: fix length calculation for converted unicode readdir names

commit f12f98dba6ea1517cd7fbb912208893b9c014c15 upstream.

cifs_from_ucs2 returns the length of the converted name, including the
length of the NULL terminator. We don't want to include the NULL
terminator in the dentry name length however since that'll throw off the
hash calculation for the dentry cache.

I believe that this is the root cause of several problems that have
cropped up recently that seem to be papered over with the "noserverino"
mount option. More confirmation of that would be good, but this is
clearly a bug and it fixes at least one reproducible problem that
was reported.

This patch fixes at least this reproducer in this kernel.org bug:

    http://bugzilla.kernel.org/show_bug.cgi?id=15088#c12

Reported-by: Bjorn Tore Sund <bjorn.sund@it.uib.no>
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index f84062f9a9850a9fa4f38a5b4ec9f657c42ae474..f5618f8cc462912c0e4cd9ed91c9e480ff3fd398 100644 (file)
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -666,6 +666,7 @@ static int cifs_get_name_from_search_buf(struct qstr *pqst,
                                           min(len, max_len), nlt,
                                           cifs_sb->mnt_cifs_flags &
                                                CIFS_MOUNT_MAP_SPECIAL_CHR);
+               pqst->len -= nls_nullsize(nlt);
        } else {
                pqst->name = filename;
                pqst->len = len;