From: ebiederm@xmission.com (Eric W. Biederman)
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org
Subject: Re: [kernel-hardening] Re: 2015 kernel CVEs
Date: Tue, 19 Jan 2016 16:41:55 -0600 [thread overview]
Message-ID: <87h9i95gzw.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <20160119180009.GT17997@ZenIV.linux.org.uk> (Al Viro's message of "Tue, 19 Jan 2016 18:00:09 +0000")
Al Viro <viro@ZenIV.linux.org.uk> writes:
> On Tue, Jan 19, 2016 at 02:28:12PM +0300, Dan Carpenter wrote:
>> CVE-2015-4178 820f9f147dcc: fs_pin: uninitialized data
>
> Why is that a CVE? Affected code is in pin_remove(), which is only
> called from fs_pin ->kill() instances; if one is _ever_ called more
> than once per fs_pin lifetime, we are already FUBAR. If Eric had
> ever intended to add checks for hlist_unhashed() on those lists,
> such checks never had been added to the tree. They definitely did not
> exist at the moment when that commit went in.
>
> It got merged mostly on the "it doesn't harm anything and it's a bit
> more tidy that way" basis; if it had ever changed behaviour in any visible
> way, *THEN* we had a real problem and that problem was not fixed by that
> commit, so I would really like to see the details - simply to make sure
> that the damn thing had been eventually fixed.
>
> Eric, could you explain? And could whoever'd been responsible for
> that CVE describe the process that had lead to its creation?
As best I know this was an issue because someone borked a backport,
and skipped this patch.
As I recall hlist_del_init was needed because in one instance one of the
lists was not used. Which is actually what it says in the description
of 820f9f147dcc so I will leave it at that.
Eric
next prev parent reply other threads:[~2016-01-19 22:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160119124917.6058019b@pc1>
2016-01-19 11:28 ` Dan Carpenter
2016-01-19 14:56 ` One Thousand Gnomes
2016-01-19 16:32 ` [kernel-hardening] " Ben Hutchings
2016-01-19 17:54 ` Greg KH
2016-01-20 17:05 ` Ben Hutchings
2016-01-20 18:04 ` Greg KH
2016-01-21 15:18 ` Jiri Kosina
2016-01-21 18:46 ` Ben Hutchings
2016-01-19 16:57 ` Peter Hurley
2016-01-19 17:00 ` Josh Boyer
2016-01-19 17:51 ` Greg KH
2016-01-20 7:12 ` [kernel-hardening] " Marcus Meissner
2016-01-19 17:57 ` [kernel-hardening] " Theodore Ts'o
2016-01-19 18:00 ` Al Viro
2016-01-19 22:41 ` Eric W. Biederman [this message]
2016-01-19 22:47 ` [kernel-hardening] " Eric W. Biederman
2016-01-20 20:11 ` Jann Horn
2016-01-20 21:26 ` One Thousand Gnomes
2016-01-19 23:35 ` Kees Cook
2016-01-20 9:57 ` Miroslav Benes
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