Re: [PATCH v3 02/11] coresight: etm4x: Fix input validation for sysfs.

Mathieu Poirier
2019-10-17T18:02:06Z

On Tue, Oct 15, 2019 at 10:19:55PM +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.
>
> Reviewed-by: Leo Yan <leo.yan@linaro.org>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Mike Leach <mike.leach@linaro.org>
> Fixes: a77de2637c9eb ("coresight: etm4x: moving sysFS entries to a dedicated file")
> Cc: stable <stable@vger.kernel.org> # 4.9+
> ---
> .../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..cc8156318018 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.
> */
> - 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[15:8] 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;

This one too, no need to send again.

> }
> --
> 2.17.1
>