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: 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>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 4f35b43..51f066a 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1464,6 +1464,9 @@
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 @@
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__,