From: Takashi Iwai Subject: Re: [PATCH] ALSA: rme9652: Fix potential Spectre v1 vulnerability Date: Wed, 19 Dec 2018 14:37:23 +0100 Message-ID: References: <20181218171834.GA14211@embeddedor> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <20181218171834.GA14211@embeddedor> Sender: linux-kernel-owner@vger.kernel.org To: " Gustavo A. R. Silva " Cc: Jaroslav Kysela , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org List-Id: alsa-devel@alsa-project.org On Tue, 18 Dec 2018 18:18:34 +0100, Gustavo A. R. Silva wrote: > > info->channel is indirectly controlled by user-space, hence leading to > a potential exploitation of the Spectre variant 1 vulnerability. > > This issue was detected with the help of Smatch: > > sound/pci/rme9652/hdsp.c:4100 snd_hdsp_channel_info() warn: potential spectre issue 'hdsp->channel_map' [r] (local cap) > > Fix this by sanitizing info->channel before using it to index hdsp->channel_map > > Notice that given that speculation windows are large, the policy is > to kill the speculation on the first load and not worry if it can be > completed with a dependent load/store [1]. > > Also, notice that I refactored the code a bit in order to get rid of the > following checkpatch warning: > > ERROR: do not use assignment in if condition > FILE: sound/pci/rme9652/hdsp.c:4103: > if ((mapped_channel = hdsp->channel_map[info->channel]) < 0) > > > [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 > > Cc: stable@vger.kernel.org > Signed-off-by: Gustavo A. R. Silva Applied, thanks. Takashi