From: Bjorn Helgaas <helgaas@kernel.org>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Kurt Schwemmer <kurt.schwemmer@microsemi.com>,
Logan Gunthorpe <logang@deltatee.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] switchtec: Fix potential Spectre v1
Date: Wed, 5 Sep 2018 16:29:47 -0500 [thread overview]
Message-ID: <20180905212947.GU107892@bhelgaas-glaptop.roam.corp.google.com> (raw)
In-Reply-To: <20180816190646.GA9610@embeddedor.com>
On Thu, Aug 16, 2018 at 02:06:46PM -0500, 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@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Applied with Logan's ack to for-linus for v4.19, thanks!
> ---
> drivers/pci/switch/switchtec.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
> index 9940cc7..54a8b30 100644
> --- a/drivers/pci/switch/switchtec.c
> +++ b/drivers/pci/switch/switchtec.c
> @@ -14,6 +14,8 @@
> #include <linux/poll.h>
> #include <linux/wait.h>
>
> +#include <linux/nospec.h>
> +
> MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCIe Management Driver");
> MODULE_VERSION("0.1");
> MODULE_LICENSE("GPL");
> @@ -909,6 +911,8 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev,
> default:
> if (p.port > ARRAY_SIZE(pcfg->dsp_pff_inst_id))
> return -EINVAL;
> + p.port = array_index_nospec(p.port,
> + ARRAY_SIZE(pcfg->dsp_pff_inst_id) + 1);
> p.pff = ioread32(&pcfg->dsp_pff_inst_id[p.port - 1]);
> break;
> }
> --
> 2.7.4
>
prev parent reply other threads:[~2018-09-05 21:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-16 19:06 [PATCH] switchtec: Fix potential Spectre v1 Gustavo A. R. Silva
2018-08-16 21:44 ` Logan Gunthorpe
2018-09-05 21:29 ` Bjorn Helgaas [this message]
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