ptp: reduce stack usage when measuring the system time offset
This patch removes the large buffer from the stack of the system
offset ioctl and replaces it with a kmalloced buffer.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 9d7542e..34a0c60 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -34,7 +34,7 @@
{
struct ptp_clock_caps caps;
struct ptp_clock_request req;
- struct ptp_sys_offset sysoff;
+ struct ptp_sys_offset *sysoff = NULL;
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
struct ptp_clock_info *ops = ptp->info;
struct ptp_clock_time *pct;
@@ -94,17 +94,22 @@
break;
case PTP_SYS_OFFSET:
- if (copy_from_user(&sysoff, (void __user *)arg,
- sizeof(sysoff))) {
+ sysoff = kmalloc(sizeof(*sysoff), GFP_KERNEL);
+ if (!sysoff) {
+ err = -ENOMEM;
+ break;
+ }
+ if (copy_from_user(sysoff, (void __user *)arg,
+ sizeof(*sysoff))) {
err = -EFAULT;
break;
}
- if (sysoff.n_samples > PTP_MAX_SAMPLES) {
+ if (sysoff->n_samples > PTP_MAX_SAMPLES) {
err = -EINVAL;
break;
}
- pct = &sysoff.ts[0];
- for (i = 0; i < sysoff.n_samples; i++) {
+ pct = &sysoff->ts[0];
+ for (i = 0; i < sysoff->n_samples; i++) {
getnstimeofday(&ts);
pct->sec = ts.tv_sec;
pct->nsec = ts.tv_nsec;
@@ -117,7 +122,7 @@
getnstimeofday(&ts);
pct->sec = ts.tv_sec;
pct->nsec = ts.tv_nsec;
- if (copy_to_user((void __user *)arg, &sysoff, sizeof(sysoff)))
+ if (copy_to_user((void __user *)arg, sysoff, sizeof(*sysoff)))
err = -EFAULT;
break;
@@ -125,6 +130,8 @@
err = -ENOTTY;
break;
}
+
+ kfree(sysoff);
return err;
}