Subject: Re: [PATCH 2/8] coresight: etm4x: Fix input validation for sysfs.

From: Mathieu Poirier <[email-masked]>
Date: Mon, 26 Aug 2019 16:29:12 -0600

On Mon, Aug 19, 2019 at 09:57:14PM +0100, Mike Leach wrote:
> A number of issues are fixed relating to sysfs input validation:-
> 
> 1) bb_ctrl_store() - incorrect compare of bit select field to absolute
> value. Reworked per ETMv4 specification.
> 2) seq_event_store() - incorrect mask value - register has two
> event values.
> 3) cyc_threshold_store() - must mask with max before checking min
> otherwise wrapped values can set illegal value below min.
> 4) res_ctrl_store() - update to mask off all res0 bits.
> 
> Signed-off-by: Mike Leach <[email-masked]>
> ---
>  .../coresight/coresight-etm4x-sysfs.c         | 21 ++++++++++++-------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> index b6984be0c515..fa1d6a938f6c 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> @@ -652,10 +652,13 @@ static ssize_t cyc_threshold_store(struct device *dev,
>  
>  	if (kstrtoul(buf, 16, &val))
>  		return -EINVAL;
> +
> +	/* mask off max threshold before checking min value */
> +	val &= ETM_CYC_THRESHOLD_MASK;
>  	if (val < drvdata->ccitmin)
>  		return -EINVAL;
>  
> -	config->ccctlr = val & ETM_CYC_THRESHOLD_MASK;
> +	config->ccctlr = val;
>  	return size;
>  }
>  static DEVICE_ATTR_RW(cyc_threshold);
> @@ -686,14 +689,16 @@ static ssize_t bb_ctrl_store(struct device *dev,
>  		return -EINVAL;
>  	if (!drvdata->nr_addr_cmp)
>  		return -EINVAL;
> +
>  	/*
> -	 * Bit[7:0] selects which address range comparator is used for
> -	 * branch broadcast control.
> +	 * Bit[8] controls include(1) / exclude(0), bits[0-7] select
> +	 * individual range comparators. If include then at least 1
> +	 * range must be  selected.

s/"must be  selected"/"must be selected"

>  	 */
> -	if (BMVAL(val, 0, 7) > drvdata->nr_addr_cmp)
> +	if ((val & BIT(8)) && (BMVAL(val, 0, 7) == 0))
>  		return -EINVAL;
>  
> -	config->bb_ctrl = val;
> +	config->bb_ctrl = val & GENMASK(8, 0);
>  	return size;
>  }
>  static DEVICE_ATTR_RW(bb_ctrl);
> @@ -1324,8 +1329,8 @@ static ssize_t seq_event_store(struct device *dev,
>  
>  	spin_lock(&drvdata->spinlock);
>  	idx = config->seq_idx;
> -	/* RST, bits[7:0] */
> -	config->seq_ctrl[idx] = val & 0xFF;
> +	/* Seq control has two masks B[15:5] F[7:0] */
> +	config->seq_ctrl[idx] = val & 0xFFFF;
>  	spin_unlock(&drvdata->spinlock);
>  	return size;
>  }
> @@ -1580,7 +1585,7 @@ static ssize_t res_ctrl_store(struct device *dev,
>  	if (idx % 2 != 0)
>  		/* PAIRINV, bit[21] */
>  		val &= ~BIT(21);
> -	config->res_ctrl[idx] = val;
> +	config->res_ctrl[idx] = val & GENMASK(21, 0);
>  	spin_unlock(&drvdata->spinlock);
>  	return size;
>  }

With the above:

Reviewed-by: Mathieu Poirier <[email-masked]>

> -- 
> 2.17.1

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