2013-09-24 07:07:55

by Dong Zhu

Subject: [PATCH] ptp: add range check on n_samples

>From d4eb97e8d5def76d46167c91059147e2c7d33433 Mon Sep 17 00:00:00 2001

When using PTP_SYS_OFFSET ioctl to measure the time offset between the
PHC and system clock, we need to specify the number of measurements, the
valid value of n_samples is between 1 to 25. If n_samples <= 0 or > 25
it makes no sense, so this patch intends to add a range check.

Signed-off-by: Dong Zhu <[email protected]>
---
drivers/ptp/ptp_chardev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 34a0c60..4e85b23 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -104,7 +104,8 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -EFAULT;
break;
}
- if (sysoff->n_samples > PTP_MAX_SAMPLES) {
+ if (sysoff->n_samples <= 0 ||
+ sysoff->n_samples > PTP_MAX_SAMPLES) {
err = -EINVAL;
break;
}
--
1.7.11.7

--
Best Regards,
Dong Zhu

2013-09-24 12:51:21

by Richard Cochran

Subject: Re: [PATCH] ptp: add range check on n_samples

On Tue, Sep 24, 2013 at 03:05:57PM +0800, Dong Zhu wrote:
> From d4eb97e8d5def76d46167c91059147e2c7d33433 Mon Sep 17 00:00:00 2001
>
> When using PTP_SYS_OFFSET ioctl to measure the time offset between the
> PHC and system clock, we need to specify the number of measurements, the
> valid value of n_samples is between 1 to 25. If n_samples <= 0 or > 25
> it makes no sense, so this patch intends to add a range check.

The field, n_samples, is unsigned, so the check is not needed.

Thanks,
Richard

> Signed-off-by: Dong Zhu <[email protected]>
> ---
> drivers/ptp/ptp_chardev.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
> index 34a0c60..4e85b23 100644
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -104,7 +104,8 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
> err = -EFAULT;
> break;
> }
> - if (sysoff->n_samples > PTP_MAX_SAMPLES) {
> + if (sysoff->n_samples <= 0 ||
> + sysoff->n_samples > PTP_MAX_SAMPLES) {
> err = -EINVAL;
> break;
> }
> --
> 1.7.11.7
>
> --
> Best Regards,
> Dong Zhu