tty: fix race in tty_fasync
We need to keep the lock held over the call to __f_setown() to
prevent a PID race.
Thanks to Al Viro for pointing out the problem, and to Travis for
making us look here in the first place.
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Julien Tinnes <jln@google.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index f15df40..c6f3b48 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1951,8 +1951,8 @@
pid = task_pid(current);
type = PIDTYPE_PID;
}
- spin_unlock_irqrestore(&tty->ctrl_lock, flags);
retval = __f_setown(filp, pid, type, 0);
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
if (retval)
goto out;
} else {
