SELinux: properly handle empty tty_files list

[safe/jmp/linux-2.6] / security / selinux / hooks.c

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 3e3fde7..f85597a 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2126,14 +2126,16 @@ static inline void flush_unauthorized_files(struct files_struct *files)
        tty = get_current_tty();
        if (tty) {
                file_list_lock();
-               file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list);
-               if (file) {
+               if (!list_empty(&tty->tty_files)) {
+                       struct inode *inode;
+
                        /* Revalidate access to controlling tty.
                           Use inode_has_perm on the tty inode directly rather
                           than using file_has_perm, as this particular open
                           file may belong to another process and we are only
                           interested in the inode-based check here. */
-                       struct inode *inode = file->f_path.dentry->d_inode;
+                       file = list_first_entry(&tty->tty_files, struct file, f_u.fu_list);
+                       inode = file->f_path.dentry->d_inode;
                        if (inode_has_perm(current, inode,
                                           FILE__READ | FILE__WRITE, NULL)) {
                                drop_tty = 1;