From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Andi Kleen <ak@linux.intel.com>, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
netdev@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 06/18] x86, barrier: stop speculation for failed access_ok
Date: Sun, 7 Jan 2018 18:57:35 -0800 [thread overview]
Message-ID: <20180108025732.2mnqgqivnh5u5mfb@ast-mbp> (raw)
In-Reply-To: <20180107135935.6ecfabd5@alans-desktop>
On Sun, Jan 07, 2018 at 01:59:35PM +0000, Alan Cox wrote:
> > which means that POC is relying 64-bit address speculation.
> > In the places coverity found the user supplied value is 32-bit,
>
> People have 32bit computers as well as 64bit and in some cases 32bit is
> fine for an attack depending where your target is relative to the object.
right. absolutely correct on 32-bit archs.
The question whether truncation to 32-bit is enough to workaround
spectre1 on 64-bit archs.
I hope the researchers can clarify.
> lfence timing is also heavily dependent upon what work has to be done to
> retire previous live instructions.
> BPF does not normally do a lot of writing so you'd expect the cost to be low.
right. to retire previous loads. Not sure what 'not a lot of writing'
has to do with lfence.
Our XDP based DDOS mostly does reads with few writes for stats into maps,
whereas XDP based load balancer modifies every packet.
XDP is root only, so not relevant in the spectre context. Just clarifying
read vs writes in BPF.
next prev parent reply other threads:[~2018-01-08 2:57 UTC|newest]
Thread overview: 162+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-06 1:09 [PATCH 00/18] prevent bounds-check bypass via speculative execution Dan Williams
2018-01-06 1:09 ` [PATCH 01/18] asm-generic/barrier: add generic nospec helpers Dan Williams
2018-01-06 2:55 ` Linus Torvalds
2018-01-06 5:23 ` Dan Williams
2018-01-06 17:08 ` Mark Rutland
2018-01-06 1:10 ` [PATCH 02/18] Documentation: document " Dan Williams
2018-01-08 16:29 ` Jonathan Corbet
2018-01-08 17:09 ` Mark Rutland
2018-01-08 21:19 ` Jonathan Corbet
2018-01-06 1:10 ` [PATCH 03/18] arm64: implement nospec_ptr() Dan Williams
2018-01-06 1:10 ` [PATCH 04/18] arm: " Dan Williams
2018-01-10 2:04 ` Laura Abbott
2018-01-10 7:40 ` Hanjun Guo
2018-01-10 17:24 ` Laura Abbott
2018-01-06 1:10 ` [PATCH 05/18] x86: implement nospec_barrier() Dan Williams
2018-01-06 1:10 ` [PATCH 06/18] x86, barrier: stop speculation for failed access_ok Dan Williams
2018-01-06 2:52 ` Linus Torvalds
2018-01-06 3:09 ` Linus Torvalds
2018-01-06 23:31 ` Dan Williams
2018-01-07 1:20 ` Linus Torvalds
2018-01-08 21:09 ` Dan Williams
2018-01-08 23:44 ` Linus Torvalds
2018-01-08 23:53 ` Dan Williams
2018-01-06 5:47 ` Dan Williams
2018-01-06 12:32 ` Alan Cox
2018-01-06 17:56 ` Linus Torvalds
2018-01-06 18:13 ` Alexei Starovoitov
2018-01-06 18:29 ` Dan Williams
2018-01-06 18:39 ` Alexei Starovoitov
2018-01-06 18:54 ` Dan Williams
2018-01-06 19:25 ` Alexei Starovoitov
2018-01-06 19:36 ` Dan Williams
2018-01-06 19:41 ` Thomas Gleixner
2018-01-08 10:02 ` Andrea Arcangeli
2018-01-06 18:38 ` Alan Cox
2018-01-06 18:51 ` Alexei Starovoitov
2018-01-06 19:55 ` Alan Cox
2018-01-06 20:09 ` Alexei Starovoitov
2018-01-06 20:22 ` Alan Cox
2018-01-06 21:17 ` Alexei Starovoitov
2018-01-06 21:21 ` Thomas Gleixner
2018-01-06 23:05 ` Alan Cox
2018-01-07 3:38 ` Alexei Starovoitov
2018-01-07 6:33 ` Willy Tarreau
2018-01-07 19:47 ` Linus Torvalds
2018-01-07 20:12 ` Willy Tarreau
2018-01-07 20:17 ` Linus Torvalds
2018-01-07 20:56 ` Thomas Gleixner
2018-01-08 2:23 ` David Miller
2018-01-08 7:38 ` Greg KH
2018-01-07 22:15 ` Willy Tarreau
2018-01-07 20:15 ` Dan Williams
2018-01-08 2:24 ` Alexei Starovoitov
2018-01-08 9:51 ` Peter Zijlstra
2018-01-08 18:21 ` Ingo Molnar
2018-01-08 12:00 ` David Laight
2018-01-08 12:12 ` Alan Cox
2018-01-08 12:33 ` David Laight
2018-01-07 10:08 ` Thomas Gleixner
2018-01-08 2:09 ` Alexei Starovoitov
2018-01-07 13:59 ` Alan Cox
2018-01-08 2:57 ` Alexei Starovoitov [this message]
2018-01-08 9:57 ` Peter Zijlstra
2018-01-06 20:42 ` Willy Tarreau
2018-01-07 1:36 ` David Miller
2018-01-07 17:19 ` James Bottomley
2018-01-07 18:31 ` Thomas Gleixner
2018-01-08 2:04 ` David Miller
2018-01-07 19:24 ` Alan Cox
2018-01-09 21:41 ` Josh Poimboeuf
2018-01-09 21:47 ` Dan Williams
2018-01-09 21:49 ` Josh Poimboeuf
2018-01-09 21:59 ` Dan Williams
2018-01-09 22:23 ` Josh Poimboeuf
2018-01-09 22:35 ` Dan Williams
2018-01-06 1:10 ` [PATCH 07/18] [media] uvcvideo: prevent bounds-check bypass via speculative execution Dan Williams
2018-01-06 9:09 ` Greg KH
2018-01-06 9:40 ` Greg KH
2018-01-06 17:41 ` Dan Williams
2018-01-07 9:09 ` Greg KH
2018-01-07 19:37 ` Dan Williams
2018-01-09 8:40 ` Laurent Pinchart
2018-01-09 10:04 ` Greg KH
2018-01-09 14:26 ` Laurent Pinchart
2018-01-09 14:47 ` Greg KH
2018-01-08 11:23 ` Laurent Pinchart
2018-01-09 2:11 ` Dan Williams
2018-01-06 1:10 ` [PATCH 08/18] carl9170: " Dan Williams
2018-01-06 10:01 ` Sergei Shtylyov
2018-01-06 14:23 ` Christian Lamparter
2018-01-06 15:06 ` Alan Cox
2018-01-06 16:38 ` Christian Lamparter
2018-01-06 16:34 ` Dan Williams
2018-01-06 1:10 ` [PATCH 09/18] p54: " Dan Williams
2018-01-06 10:01 ` Sergei Shtylyov
2018-01-06 1:10 ` [PATCH 10/18] qla2xxx: " Dan Williams
2018-01-06 9:03 ` Greg KH
2018-01-06 9:42 ` Greg KH
2018-01-11 22:15 ` Dan Williams
2018-01-12 7:27 ` Greg KH
2018-01-12 15:25 ` James Bottomley
2018-01-06 1:10 ` [PATCH 11/18] cw1200: " Dan Williams
2018-01-06 1:10 ` [PATCH 12/18] Thermal/int340x: " Dan Williams
2018-01-06 1:53 ` Srinivas Pandruvada
2018-01-06 1:57 ` Dan Williams
2018-01-06 17:24 ` Srinivas Pandruvada
2018-01-06 10:03 ` Sergei Shtylyov
2018-01-06 1:11 ` [PATCH 13/18] ipv6: " Dan Williams
2018-01-06 10:04 ` Sergei Shtylyov
2018-01-06 14:48 ` Stephen Hemminger
2018-01-06 18:05 ` Dan Williams
2018-01-06 1:11 ` [PATCH 14/18] ipv4: " Dan Williams
2018-01-06 9:00 ` Greg KH
2018-01-06 9:01 ` Greg KH
2018-01-06 12:23 ` Alan Cox
2018-01-06 15:14 ` Greg KH
2018-01-06 16:29 ` Dan Williams
2018-01-06 18:10 ` Dan Williams
2018-01-06 10:04 ` Sergei Shtylyov
2018-01-06 1:11 ` [PATCH 15/18] vfs, fdtable: " Dan Williams
2018-01-06 10:05 ` Sergei Shtylyov
2018-01-06 1:11 ` [PATCH 16/18] net: mpls: " Dan Williams
2018-01-06 10:06 ` Sergei Shtylyov
2018-01-09 3:11 ` Eric W. Biederman
2018-01-09 3:42 ` Dan Williams
2018-01-09 4:13 ` Linus Torvalds
2018-01-09 4:21 ` Linus Torvalds
2018-01-10 0:48 ` Dan Williams
2018-01-10 1:33 ` Dan Williams
2018-01-10 1:57 ` Alexei Starovoitov
2018-01-10 2:22 ` Dan Williams
2018-01-10 3:07 ` Alexei Starovoitov
2018-01-10 3:27 ` Linus Torvalds
2018-01-09 16:17 ` Eric W. Biederman
2018-01-09 18:01 ` Dan Williams
2018-01-10 0:54 ` Eric W. Biederman
2018-01-10 1:31 ` Dan Williams
2018-01-06 1:11 ` [PATCH 17/18] udf: " Dan Williams
2018-01-08 10:20 ` Jan Kara
2018-01-06 1:11 ` [PATCH 18/18] userns: " Dan Williams
2018-01-06 2:22 ` [PATCH 00/18] " Eric W. Biederman
2018-01-06 6:30 ` Dan Williams
2018-01-08 10:08 ` Peter Zijlstra
2018-01-08 11:14 ` Laurent Pinchart
2018-01-08 11:43 ` Alan Cox
2018-01-08 11:55 ` Peter Zijlstra
2018-01-08 18:33 ` Ingo Molnar
2018-01-08 16:20 ` Bart Van Assche
2018-01-06 18:56 ` Florian Fainelli
2018-01-06 18:59 ` Arjan van de Ven
2018-01-06 19:37 ` Dan Williams
2018-01-06 20:07 ` Dan Williams
2018-01-08 4:49 ` Bart Van Assche
2018-01-08 13:33 ` Arjan van de Ven
2018-01-09 19:34 ` Jiri Kosina
2018-01-09 19:44 ` Dan Williams
2018-01-09 20:55 ` Josh Poimboeuf
2018-01-11 9:54 ` Jiri Kosina
2018-01-11 15:58 ` Dan Williams
2018-01-11 16:34 ` Daniel Borkmann
2018-01-13 11:33 ` QingFeng Hao
2018-01-09 0:12 [PATCH 06/18] x86, barrier: stop speculation for failed access_ok Linus Torvalds
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