[05/29] tty: fix race in tty_fasync

From: Greg KH
Date: Fri Jan 22 2010 - 19:29:53 EST

2.6.32-stable review patch. If anyone has any objections, please let us know.


From: Greg Kroah-Hartman <gregkh@xxxxxxx>

commit 703625118069f9f8960d356676662d3db5a9d116 upstream.

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@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Tavis Ormandy <taviso@xxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Julien Tinnes <jln@xxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

drivers/char/tty_io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1930,8 +1930,8 @@ static int tty_fasync(int fd, struct fil
pid = task_pid(current);
- 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 {

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/