Re: [PATCH v2] tty: Prevent hw state corruption in exclusive mode reopen
From: Shreyas Bethur <hidden>
Date: 2015-01-07 22:55:10
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Peter Hurley [off-list ref] wrote on 12/30/2014 09:39:25 AM:
From: Peter Hurley <redacted> To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Cc: Jiri Slaby <redacted>, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Shreyas Bethur [off-list ref], Peter Hurley [off-list ref] Date: 12/30/2014 09:39 AM Subject: [PATCH v2] tty: Prevent hw state corruption in exclusive mode
reopen
quoted hunk ↗ jump to hunk
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 <redacted> Signed-off-by: Peter Hurley <redacted> --- drivers/tty/tty_io.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)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 @@ 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__,-- 2.2.1
Acked-by: Shreyas Bethur <redacted>