linux-kernel - Re: pty: fix use after free/oops at pty_unix98

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]

Message-ID: <20151215163604.GA20334@dhcppc10.redhat.com>
Date:	Tue, 15 Dec 2015 14:36:04 -0200
From:	"Herton R. Krzesinski" <herton@...hat.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>
Subject: Re: pty: fix use after free/oops at pty_unix98_shutdown

On Tue, Dec 15, 2015 at 08:17:56AM -0800, Peter Hurley wrote:
> > I also expect in a rare case where all ptmx references are gone/closed, this also
> > could happen on final close when the master tty is given to pty_unix98_shutdown.
> 
> This logic I'm not following. If the pty master is being released, then the inode
> is valid for the release() operation in-progress.

Hi Peter,

yes, you're right if you are eg. closing the /dev/ptmx or /dev/pts/ptmx file
previously opened. But I thought and refer above to the case where for example
you are closing /dev/tty and that's the final close and there is no other
process in the system with the /dev/{,*/}ptmx opened, the inode which referenced
the previously opened ptmx could be gone. It would be rare though since in a
running system any logged in user eg. through ssh or with a terminal open in X
will have at least a ptmx device opened.

> 
> Regards,
> Peter Hurley
>

-- 
[]'s
Herton 
--
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/