From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: [PATCH] tty: Prevent hw state corruption in exclusive mode reopen Date: Tue, 30 Dec 2014 07:34:33 -0500 Message-ID: <1419942873-6779-1-git-send-email-peter@hurleysoftware.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Shreyas Bethur , Peter Hurley List-Id: linux-serial@vger.kernel.org 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 Signed-off-by: Peter Hurley --- drivers/tty/tty_io.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 4f35b43..8629087 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -2091,6 +2091,11 @@ retry_open: goto err_file; } + if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN)) { + retval = -EBUSY; + goto err_file; + } + tty_add_file(tty, filp); check_tty_count(tty, __func__); @@ -2106,10 +2111,6 @@ 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__, -- 2.2.1