linux-kernel - Re: [PATCH] switchtec: Fix potential Spectre v1

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Message-ID: <9a8fe29a-741e-c7ca-a844-ac6a8104211e@deltatee.com>
Date:   Thu, 16 Aug 2018 15:44:04 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Kurt Schwemmer <kurt.schwemmer@...rosemi.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] switchtec: Fix potential Spectre v1



On 16/08/18 01:06 PM, Gustavo A. R. Silva wrote:
> p.port can 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:
> 
> drivers/pci/switch/switchtec.c:912 ioctl_port_to_pff() warn: potential
> spectre issue 'pcfg->dsp_pff_inst_id' [r]
> 
> Fix this by sanitizing p.port before using it to index
> pcfg->dsp_pff_inst_id
> 
> 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].
> 
> [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Acked-by: Logan Gunthorpe <logang@...tatee.com>

Looks good to me, thanks.

Logan