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Commit 86f2c00f authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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tty: Prevent hw state corruption in exclusive mode reopen 



Exclusive mode ttys (TTY_EXCLUSIVE) do not allow further reopens;
fail the condition before associating the file pointer and calling
the driver open() method.

Prevents DTR programming when the tty is already in exclusive mode.

Reported-by: default avatarShreyas Bethur <shreyas.bethur@ni.com>
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Acked-by: default avatarShreyas Bethur <shreyas.bethur@ni.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 72a3c0e4

drivers/tty/tty_io.c

+3 −4
Original line number Diff line number Diff line
@@ -1464,6 +1464,9 @@ static int tty_reopen(struct tty_struct *tty) 
	    driver->subtype == PTY_TYPE_MASTER)

		return -EIO;



	if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))

		return -EBUSY;



	tty->count++;



	WARN_ON(!tty->ldisc);
@@ -2106,10 +2109,6 @@ static int tty_open(struct inode *inode, struct file *filp) 
		retval = -ENODEV;

	filp->f_flags = saved_flags;



	if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&

						!capable(CAP_SYS_ADMIN))

		retval = -EBUSY;



	if (retval) {

#ifdef TTY_DEBUG_HANGUP

		printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,