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From: Peter Zijlstra <peterz@infradead.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1
Date: Tue, 24 Apr 2018 13:21:29 +0200	[thread overview]
Message-ID: <20180424112129.GT4129@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180424103609.GD4064@hirez.programming.kicks-ass.net>

On Tue, Apr 24, 2018 at 12:36:09PM +0200, Peter Zijlstra wrote:
> 
> Then usespace probes which part of the descr[] array is now in cache and
> from that it can infer the initial out-of-bound value.

Just had a better look at v4l_fill_fmtdesc() and actually read the
comment. The code cannot be compiled as a array because it is big and
sparse. But the log(n) condition tree is a prime candidate for the
branchscope side-channel, which would be able to reconstruct a
significant number of bits of the original value. A denser tree gives
more bits etc.

  reply	other threads:[~2018-04-24 11:21 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-23 17:37 [PATCH 00/11] fix potential Spectre variant 1 issues Gustavo A. R. Silva
2018-04-23 17:37 ` Gustavo A. R. Silva
2018-04-23 17:38 ` [PATCH 01/11] media: tm6000: fix potential Spectre variant 1 Gustavo A. R. Silva
2018-04-23 18:24   ` Mauro Carvalho Chehab
2018-04-23 19:11     ` Gustavo A. R. Silva
2018-04-23 19:17       ` Mauro Carvalho Chehab
2018-04-23 19:22         ` Gustavo A. R. Silva
2018-04-26 21:41         ` Gustavo A. R. Silva
2018-04-26 23:42           ` Mauro Carvalho Chehab
2018-05-15  3:31             ` Gustavo A. R. Silva
2018-05-15 11:59               ` Mauro Carvalho Chehab
2018-05-15 14:16                 ` Dan Carpenter
2018-05-15 17:29                   ` Gustavo A. R. Silva
2018-05-15 19:00                     ` Mauro Carvalho Chehab
2018-05-16 13:11                       ` Dan Carpenter
2018-05-16 13:36                         ` Mauro Carvalho Chehab
2018-05-15 19:39                     ` Dan Carpenter
2018-05-17  1:14                       ` Gustavo A. R. Silva
2018-05-17 10:36                         ` Gustavo A. R. Silva
2018-05-17 11:34                           ` Mauro Carvalho Chehab
2018-05-17 11:43                             ` Mauro Carvalho Chehab
2018-05-17 12:13                               ` Mauro Carvalho Chehab
2018-05-17 18:08                                 ` Gustavo A. R. Silva
2018-05-21 16:18                                   ` Gustavo A. R. Silva
2018-04-24  9:35     ` Dan Carpenter
2018-04-24 10:11       ` Mauro Carvalho Chehab
2018-04-24 10:36       ` Peter Zijlstra
2018-04-24 11:21         ` Peter Zijlstra [this message]
2018-04-24 17:47         ` Mauro Carvalho Chehab
2018-04-24 18:48           ` Peter Zijlstra
2018-04-23 17:38 ` [PATCH 02/11] exynos4-is: mipi-csis: " Gustavo A. R. Silva
2018-04-23 17:38   ` Gustavo A. R. Silva
2018-04-23 17:39 ` [PATCH 03/11] fsl-viu: " Gustavo A. R. Silva
2018-04-23 17:40 ` [PATCH 04/11] marvell-ccic: mcam-core: " Gustavo A. R. Silva
2018-04-23 17:41 ` [PATCH 05/11] omap_vout: " Gustavo A. R. Silva
2018-04-23 17:47 ` [PATCH 06/11] rcar-v4l2: " Gustavo A. R. Silva
2018-04-23 17:48 ` [PATCH 07/11] rcar_drif: " Gustavo A. R. Silva
2018-04-23 17:48 ` [PATCH 08/11] sh_vou: " Gustavo A. R. Silva
2018-04-23 17:50 ` [PATCH 09/11] vimc-debayer: " Gustavo A. R. Silva
2018-04-23 17:51 ` [PATCH 10/11] vivid-sdr-cap: " Gustavo A. R. Silva
2018-04-23 17:52 ` [PATCH 11/11] vsp1_rwpf: " Gustavo A. R. Silva
2018-04-23 19:13 ` [PATCH 00/11] fix potential Spectre variant 1 issues Gustavo A. R. Silva
2018-04-23 19:13   ` Gustavo A. R. Silva

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