diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2006-12-08 02:36:04 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-08 08:28:38 -0800 |
| commit | 24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517 (patch) | |
| tree | 2ff478b1925159eeac007913c2a8f19d5f5e6010 /drivers/s390/char/fs3270.c | |
| parent | 562f9c574e0707f9159a729ea41faf53b221cd30 (diff) | |
| download | linux-24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517.tar.bz2 | |
[PATCH] tty: ->signal->tty locking
Fix the locking of signal->tty.
Use ->sighand->siglock to protect ->signal->tty; this lock is already used
by most other members of ->signal/->sighand. And unless we are 'current'
or the tasklist_lock is held we need ->siglock to access ->signal anyway.
(NOTE: sys_unshare() is broken wrt ->sighand locking rules)
Note that tty_mutex is held over tty destruction, so while holding
tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys
are governed by their open file handles. This leaves some holes for tty
access from signal->tty (or any other non file related tty access).
It solves the tty SLAB scribbles we were seeing.
(NOTE: the change from group_send_sig_info to __group_send_sig_info needs to
be examined by someone familiar with the security framework, I think
it is safe given the SEND_SIG_PRIV from other __group_send_sig_info
invocations)
[schwidefsky@de.ibm.com: 3270 fix]
[akpm@osdl.org: various post-viro fixes]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Alan Cox <alan@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/s390/char/fs3270.c')
| -rw-r--r-- | drivers/s390/char/fs3270.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/s390/char/fs3270.c b/drivers/s390/char/fs3270.c index 78f8bda81dae..ef205ddd31a4 100644 --- a/drivers/s390/char/fs3270.c +++ b/drivers/s390/char/fs3270.c @@ -424,11 +424,15 @@ fs3270_open(struct inode *inode, struct file *filp) minor = iminor(filp->f_dentry->d_inode); /* Check for minor 0 multiplexer. */ if (minor == 0) { - if (!current->signal->tty) + struct tty_struct *tty; + mutex_lock(&tty_mutex); + tty = get_current_tty(); + if (!tty || tty->driver->major != IBM_TTY3270_MAJOR) { + mutex_unlock(&tty_mutex); return -ENODEV; - if (current->signal->tty->driver->major != IBM_TTY3270_MAJOR) - return -ENODEV; - minor = current->signal->tty->index + RAW3270_FIRSTMINOR; + } + minor = tty->index + RAW3270_FIRSTMINOR; + mutex_unlock(&tty_mutex); } /* Check if some other program is already using fullscreen mode. */ fp = (struct fs3270 *) raw3270_find_view(&fs3270_fn, minor); |