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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2006-12-08 02:36:04 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 08:28:38 -0800
commit24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517 (patch)
tree2ff478b1925159eeac007913c2a8f19d5f5e6010 /drivers/s390/char/fs3270.c
parent562f9c574e0707f9159a729ea41faf53b221cd30 (diff)
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[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.c12
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);