From 2cb5998b5f0ccc886fdda3509059eef297b49577 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Mon, 13 Oct 2008 10:40:30 +0100 Subject: [PATCH] tty: the vhangup syscall is racy We now have the infrastructure to sort this out but rather than teaching the syscall tty lock rules we move the hard work into a tty helper Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/char/tty_io.c | 19 +++++++++++++++++++ fs/open.c | 3 +-- include/linux/tty.h | 1 + 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 913b50258f9..b5f57d0b30e 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -729,6 +729,25 @@ void tty_vhangup(struct tty_struct *tty) EXPORT_SYMBOL(tty_vhangup); +/** + * tty_vhangup_self - process vhangup for own ctty + * + * Perform a vhangup on the current controlling tty + */ + +void tty_vhangup_self(void) +{ + struct tty_struct *tty; + + mutex_lock(&tty_mutex); + tty = get_current_tty(); + if (tty) { + tty_vhangup(tty); + tty_kref_put(tty); + } + mutex_unlock(&tty_mutex); +} + /** * tty_hung_up_p - was tty hung up * @filp: file pointer of tty diff --git a/fs/open.c b/fs/open.c index 07da9359481..5596049863b 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1141,8 +1141,7 @@ EXPORT_SYMBOL(sys_close); asmlinkage long sys_vhangup(void) { if (capable(CAP_SYS_TTY_CONFIG)) { - /* XXX: this needs locking */ - tty_vhangup(current->signal->tty); + tty_vhangup_self(); return 0; } return -EPERM; diff --git a/include/linux/tty.h b/include/linux/tty.h index c30ed8d3bcb..e00393a3d1c 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -361,6 +361,7 @@ extern int is_ignored(int sig); extern int tty_signal(int sig, struct tty_struct *tty); extern void tty_hangup(struct tty_struct *tty); extern void tty_vhangup(struct tty_struct *tty); +extern void tty_vhangup_self(void); extern void tty_unhangup(struct file *filp); extern int tty_hung_up_p(struct file *filp); extern void do_SAK(struct tty_struct *tty); -- 2.41.0