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tty: the vhangup syscall is racy

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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 <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2008-10-13 10:40:30 +01:00 committed by Linus Torvalds
parent 216ba023a9
commit 2cb5998b5f
3 changed files with 21 additions and 2 deletions
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19
drivers/char/tty_io.c
View File

@ -729,6 +729,25 @@ void tty_vhangup(struct tty_struct *tty)
EXPORT_SYMBOL(tty_vhangup); 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 * tty_hung_up_p - was tty hung up
* @filp: file pointer of tty * @filp: file pointer of tty

3
fs/open.c
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@ -1141,8 +1141,7 @@ EXPORT_SYMBOL(sys_close);
asmlinkage long sys_vhangup(void) asmlinkage long sys_vhangup(void)
{ {
if (capable(CAP_SYS_TTY_CONFIG)) { if (capable(CAP_SYS_TTY_CONFIG)) {
/* XXX: this needs locking */ tty_vhangup_self();
tty_vhangup(current->signal->tty);
return 0; return 0;
} }
return -EPERM; return -EPERM;

1
include/linux/tty.h
View File

@ -361,6 +361,7 @@ extern int is_ignored(int sig);
extern int tty_signal(int sig, struct tty_struct *tty); extern int tty_signal(int sig, struct tty_struct *tty);
extern void tty_hangup(struct tty_struct *tty); extern void tty_hangup(struct tty_struct *tty);
extern void tty_vhangup(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 void tty_unhangup(struct file *filp);
extern int tty_hung_up_p(struct file *filp); extern int tty_hung_up_p(struct file *filp);
extern void do_SAK(struct tty_struct *tty); extern void do_SAK(struct tty_struct *tty);