lkml.org 
[lkml]   [2010]   [Jan]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [06/11] tty: fix race in tty_fasync
From
Date
Greg KH <gregkh@suse.de> writes:

> 2.6.27-stable review patch. If anyone has any objections, please let us know.

Only that __f_setown by way of f_modown unconditionally enables interrupts. So
without touching f_modown as well in mainline we have nasty sounding lockdep warnings.

Eric


> ------------------
>
> From: Greg Kroah-Hartman <gregkh@suse.de>
>
> 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@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>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
>
> ---
> 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
> @@ -2437,8 +2437,8 @@ static int tty_fasync(int fd, struct fil
> 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 {


\
 
 \ /
  Last update: 2010-01-26 20:53    [from the cache]
©2003-2011 Jasper Spaans