From 24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 8 Dec 2006 02:36:04 -0800 Subject: [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 Acked-by: Alan Cox Cc: Oleg Nesterov Cc: Prarit Bhargava Cc: Chris Wright Cc: Roland McGrath Cc: Stephen Smalley Cc: James Morris Cc: "David S. Miller" Cc: Jeff Dike Cc: Martin Schwidefsky Cc: Jan Kara Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/tty.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/tty.h b/include/linux/tty.h index f717f089823..1d29999a343 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -309,6 +309,12 @@ extern void tty_ldisc_flush(struct tty_struct *tty); extern int tty_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg); +extern dev_t tty_devnum(struct tty_struct *tty); +extern void proc_clear_tty(struct task_struct *p); +extern void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); +extern void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); +extern struct tty_struct *get_current_tty(void); + extern struct mutex tty_mutex; /* n_tty.c */ @@ -335,10 +341,5 @@ extern void console_print(const char *); extern int vt_ioctl(struct tty_struct *tty, struct file * file, unsigned int cmd, unsigned long arg); -static inline dev_t tty_devnum(struct tty_struct *tty) -{ - return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; -} - #endif /* __KERNEL__ */ #endif -- cgit v1.2.3