[PATCH] selinux: fix tty locking
Take tty_mutex when accessing ->signal->tty in selinux code. Noted by Alan
Cox. Longer term, we are looking at refactoring the code to provide better
encapsulation of the tty layer, but this is a simple fix that addresses the
immediate bug.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Alan Cox <alan@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 55cec4d..e4d81a4 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1689,10 +1689,12 @@
{
struct avc_audit_data ad;
struct file *file, *devnull = NULL;
- struct tty_struct *tty = current->signal->tty;
+ struct tty_struct *tty;
struct fdtable *fdt;
long j = -1;
+ mutex_lock(&tty_mutex);
+ tty = current->signal->tty;
if (tty) {
file_list_lock();
file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list);
@@ -1712,6 +1714,7 @@
}
file_list_unlock();
}
+ mutex_unlock(&tty_mutex);
/* Revalidate access to inherited open files. */