From: David Miller <davem@davemloft.net>
To: dborkman@redhat.com
Cc: ast@plumgrid.com, netdev@vger.kernel.org
Subject: Re: [PATCH net] net: filter: initialize A and X registers
Date: Wed, 23 Apr 2014 12:52:35 -0400 (EDT) [thread overview]
Message-ID: <20140423.125235.1748012189632512309.davem@davemloft.net> (raw)
In-Reply-To: <5357659E.1070807@redhat.com>
From: Daniel Borkmann <dborkman@redhat.com>
Date: Wed, 23 Apr 2014 09:02:54 +0200
> On 04/23/2014 06:59 AM, Alexei Starovoitov wrote:
>> On Tue, Apr 22, 2014 at 8:57 PM, David Miller <davem@davemloft.net>
>> wrote:
>>> From: Alexei Starovoitov <ast@plumgrid.com>
>>> Date: Tue, 22 Apr 2014 20:18:57 -0700
>>>
>>>> exisiting BPF verifier allows uninitialized access to registers,
>>>> 'ret A' is considered to be a valid filter.
>>>> So initialize A and X to zero to prevent leaking kernel memory
>>>> In the future BPF verifier will be rejecting such filters
>>>>
>>>> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
>>>
>>> Has the code always been like this?
>
> I think it would be much cleaner to just prevent such filters that
> only contain a 'ret A', or 'ret X' w/o a load into X from attaching.
That choice had to be done two decades ago, not now.
We have to accept such filters, we always have.
next prev parent reply other threads:[~2014-04-23 16:52 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-23 3:18 [PATCH net] net: filter: initialize A and X registers Alexei Starovoitov
2014-04-23 3:57 ` David Miller
2014-04-23 4:59 ` Alexei Starovoitov
2014-04-23 7:02 ` Daniel Borkmann
2014-04-23 16:52 ` David Miller [this message]
2014-04-23 17:20 ` Daniel Borkmann
2014-04-23 16:50 ` David Miller
2014-04-23 20:38 ` Alexei Starovoitov
2014-04-23 21:39 ` Eric Dumazet
2014-04-23 22:19 ` Alexei Starovoitov
2014-04-24 2:55 ` Eric Dumazet
2014-04-24 3:22 ` Alexei Starovoitov
2014-04-25 8:23 ` Daniel Borkmann
2014-04-24 7:07 ` Martin Schwidefsky
2014-04-23 5:13 ` Eric Dumazet
2014-04-23 11:45 ` Daniel Borkmann
2014-04-23 13:39 ` Eric Dumazet
2014-04-23 21:07 ` David Miller
2014-04-23 16:51 ` David Miller
2014-04-23 17:10 ` Daniel Borkmann
2014-04-23 17:14 ` Eric Dumazet
2014-04-24 17:24 ` David Miller
2014-04-24 18:11 ` Eric Dumazet
2014-04-24 22:18 ` Daniel Borkmann
2014-04-23 7:53 ` Daniel Borkmann
2014-04-23 16:13 ` Alexei Starovoitov
2014-04-23 19:35 ` David Miller
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