linux-kernel - Re: [PATCH v5 1/3] tty: fix data race in flush_to

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

Date:	Thu, 17 Sep 2015 13:37:53 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Andrey Konovalov <andreyknvl@...gle.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Hans Boehm <hboehm@...gle.com>
Subject: Re: [PATCH v5 1/3] tty: fix data race in flush_to_ldisc

On Thu, Sep 17, 2015 at 11:17 AM, Dmitry Vyukov <dvyukov@...gle.com> wrote:
> flush_to_ldisc reads port->itty and checks that it is not NULL,
> concurrently release_tty sets port->itty to NULL. It is possible
> that flush_to_ldisc loads port->itty once, ensures that it is
> not NULL, but then reloads it again and uses. The second load
> can already return NULL, which will cause a crash.
>
> Use READ_ONCE to read port->itty.
>
> The data race was found with KernelThreadSanitizer (KTSAN).

Reviewed-by: Peter Hurley <peter@...leysoftware.com>
--
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/