linux-kernel - [PATCH v3] tty: Add driver unthrottle in ioctl(...,TCFLSH,..).

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <50B3E897.3020901@ilyx.ru>
Date:	Tue, 27 Nov 2012 02:09:27 +0400
From:	Ilya Zykov <ilya@...x.ru>
To:	Alan Cox <alan@...ux.intel.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	ilya@...x.ru
Subject: [PATCH v3] tty: Add driver unthrottle in ioctl(...,TCFLSH,..).

Regression 'tty: fix "IRQ45: nobody cared"'
Regression commit 7b292b4bf9a9d6098440d85616d6ca4c608b8304

  Function reset_buffer_flags() also invoked during the ioctl(...,TCFLSH,..). 
At the time of request we can have full buffers and throttled driver too. 
If we don't unthrottle driver, we can get forever throttled driver, because,
after request, we will have empty buffers and throttled driver and 
there is no place to unthrottle driver.
It simple reproduce with "pty" pair then one side sleep on tty->write_wait,
and other side do ioctl(...,TCFLSH,..). Then there is no place to do writers wake up.


Signed-off-by: Ilya Zykov <ilya@...x.ru>
---

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 12b1fa0..a038be1 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -1098,10 +1098,12 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
        case TCIFLUSH:
                if (ld && ld->ops->flush_buffer)
                        ld->ops->flush_buffer(tty);
+               tty_unthrottle(tty);
                break;
        case TCIOFLUSH:
                if (ld && ld->ops->flush_buffer)
                        ld->ops->flush_buffer(tty);
+                tty_unthrottle(tty);
                /* fall through */
        case TCOFLUSH:
                tty_driver_flush_buffer(tty);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/