cifs: use the correct max-length for dentry_path_raw()

RHBZ: 1972502

PATH_MAX is 4096 but PAGE_SIZE can be >4096 on some architectures
such as ppc and would thus write beyond the end of the actual object.

Cc: <stable@vger.kernel.org>
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Suggested-by: Brian foster <bfoster@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 79402ca..5f8a302 100644 (file)
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -100,7 +100,7 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
                pplen = cifs_sb->prepath ? strlen(cifs_sb->prepath) + 1 : 0;
 
-       s = dentry_path_raw(direntry, page, PAGE_SIZE);
+       s = dentry_path_raw(direntry, page, PATH_MAX);
        if (IS_ERR(s))
                return s;
        if (!s[1])      // for root we want "", not "/"