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tty: Prevent hw state corruption in exclusive mode reopen

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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: Shreyas Bethur <shreyas.bethur@ni.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Shreyas Bethur <shreyas.bethur@ni.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2014-12-30 10:39:25 -05:00 committed by Greg Kroah-Hartman
parent 72a3c0e4e6
commit 86f2c00f1d
1 changed files with 3 additions and 4 deletions
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7
drivers/tty/tty_io.c
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@ -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 @@ retry_open:
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__,