tty: make sure that proc_clear_tty stores the cpu flags

proc_clear_tty() gets called with interrupts off (while holding the task list
lock) from sys_setid. This means that it needs the _irqsave version of the
locking primitives.

Reported-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Tested-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 7053d6333692..3f48d88cffc0 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -3032,11 +3032,12 @@ EXPORT_SYMBOL(tty_devnum);
 
 void proc_clear_tty(struct task_struct *p)
 {
+        unsigned long flags;
         struct tty_struct *tty;
-        spin_lock_irq(&p->sighand->siglock);
+        spin_lock_irqsave(&p->sighand->siglock, flags);
         tty = p->signal->tty;
         p->signal->tty = NULL;
-        spin_unlock_irq(&p->sighand->siglock);
+        spin_unlock_irqrestore(&p->sighand->siglock, flags);
         tty_kref_put(tty);
 }