drivers/ptp: Fix kernel memory disclosure

The reserved field precise_offset->rsv is not cleared before being
copied to user space, leaking kernel stack memory. Clear the struct
before it's copied.

Signed-off-by: Vlad Tsyrklevich <vlad@tsyrklevich.net>
Acked-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 d637c93..58a97d4 100644 (file)
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -193,6 +193,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
                if (err)
                        break;
 
+               memset(&precise_offset, 0, sizeof(precise_offset));
                ts = ktime_to_timespec64(xtstamp.device);
                precise_offset.device.sec = ts.tv_sec;
                precise_offset.device.nsec = ts.tv_nsec;