linux-kernel - Re: [PATCH 09/18] p54: prevent bounds-check bypass via speculative execution

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Message-ID: <834cec3e-67a6-3ddb-39a2-76e04ade3cf1@cogentembedded.com>
Date:   Sat, 6 Jan 2018 13:01:57 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org, peterz@...radead.org,
        netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        Elena Reshetova <elena.reshetova@...el.com>,
        gregkh@...uxfoundation.org,
        Christian Lamparter <chunkeey@...glemail.com>,
        tglx@...utronix.de, torvalds@...ux-foundation.org,
        Kalle Valo <kvalo@...eaurora.org>, alan@...ux.intel.com
Subject: Re: [PATCH 09/18] p54: prevent bounds-check bypass via speculative
 execution

On 1/6/2018 4:10 AM, Dan Williams wrote:

> Static analysis reports that 'queue' may be a user controlled value that
> is used as a data dependency to read from the 'priv->qos_params' array.
> In order to avoid potential leaks of kernel memory values, block
> speculative execution of the instruction stream that could issue reads
> based on an invalid result of 'priv->qos_params[queue]'.
> 
> Based on an original patch by Elena Reshetova.
> 
> Cc: Christian Lamparter <chunkeey@...glemail.com>
> Cc: Kalle Valo <kvalo@...eaurora.org>
> Cc: linux-wireless@...r.kernel.org
> Cc: netdev@...r.kernel.org
> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>   drivers/net/wireless/intersil/p54/main.c |    8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/intersil/p54/main.c b/drivers/net/wireless/intersil/p54/main.c
> index ab6d39e12069..85c9cbee35fc 100644
> --- a/drivers/net/wireless/intersil/p54/main.c
> +++ b/drivers/net/wireless/intersil/p54/main.c
[...]
> @@ -411,12 +412,13 @@ static int p54_conf_tx(struct ieee80211_hw *dev,
>   		       const struct ieee80211_tx_queue_params *params)
>   {
>   	struct p54_common *priv = dev->priv;
> +	struct p54_edcf_queue_param *p54_q;
>   	int ret;
>   
>   	mutex_lock(&priv->conf_mutex);
> -	if (queue < dev->queues) {
> -		P54_SET_QUEUE(priv->qos_params[queue], params->aifs,
> -			params->cw_min, params->cw_max, params->txop);
> +	if ((p54_q = nospec_array_ptr(priv->qos_params, queue, dev->queues))) {

    Same complaint here...

> +		P54_SET_QUEUE(p54_q[0], params->aifs, params->cw_min,
> +				params->cw_max, params->txop);
>   		ret = p54_set_edcf(priv);
>   	} else
>   		ret = -EINVAL;
> 

MBR, Sergei