From 5d0fdf1e01899805b6c2c0b789a707dcb731b1ea Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Wed, 30 Apr 2008 00:53:31 -0700 Subject: [PATCH] tty_io: fix remaining pid struct locking This fixes the last couple of pid struct locking failures I know about. [oleg@tv-sign.ru: clean up do_task_stat()] Signed-off-by: Alan Cox Signed-off-by: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/tty_io.c | 28 +++++++++++++++++++++++++++- fs/proc/array.c | 4 +++- include/linux/tty.h | 1 + 3 files changed, 31 insertions(+), 2 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index c8aa318eaa1..2460c4c7616 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -3173,6 +3173,27 @@ unlock: return ret; } +/** + * tty_get_pgrp - return a ref counted pgrp pid + * @tty: tty to read + * + * Returns a refcounted instance of the pid struct for the process + * group controlling the tty. + */ + +struct pid *tty_get_pgrp(struct tty_struct *tty) +{ + unsigned long flags; + struct pid *pgrp; + + spin_lock_irqsave(&tty->ctrl_lock, flags); + pgrp = get_pid(tty->pgrp); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + + return pgrp; +} +EXPORT_SYMBOL_GPL(tty_get_pgrp); + /** * tiocgpgrp - get process group * @tty: tty passed by user @@ -3187,13 +3208,18 @@ unlock: static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { + struct pid *pid; + int ret; /* * (tty == real_tty) is a cheap way of * testing if the tty is NOT a master pty. */ if (tty == real_tty && current->signal->tty != real_tty) return -ENOTTY; - return put_user(pid_vnr(real_tty->pgrp), p); + pid = tty_get_pgrp(real_tty); + ret = put_user(pid_vnr(pid), p); + put_pid(pid); + return ret; } /** diff --git a/fs/proc/array.c b/fs/proc/array.c index b07a71002f2..c135cbdd912 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -429,7 +429,9 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, struct signal_struct *sig = task->signal; if (sig->tty) { - tty_pgrp = pid_nr_ns(sig->tty->pgrp, ns); + struct pid *pgrp = tty_get_pgrp(sig->tty); + tty_pgrp = pid_nr_ns(pgrp, ns); + put_pid(pgrp); tty_nr = new_encode_dev(tty_devnum(sig->tty)); } diff --git a/include/linux/tty.h b/include/linux/tty.h index 381085e45cc..2699298b00e 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -297,6 +297,7 @@ extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, extern void tty_write_message(struct tty_struct *tty, char *msg); extern int is_current_pgrp_orphaned(void); +extern struct pid *tty_get_pgrp(struct tty_struct *tty); extern int is_ignored(int sig); extern int tty_signal(int sig, struct tty_struct *tty); extern void tty_hangup(struct tty_struct * tty); -- 2.20.1