drivers/pps/pps.c: clear offset flags in PPS_SETPARAMS ioctl

The PPS assert/clear offset corrections are set by the PPS_SETPARAMS
ioctl in the pps_ktime structs, which also contain flags.  The flags are
not initialized by applications (using the timepps.h header) and they
are not used by the kernel for anything except returning them back in
the PPS_GETPARAMS ioctl.

Set the flags to zero to make it clear they are unused and avoid leaking
uninitialized data of the PPS_SETPARAMS caller to other applications
that have a read access to the PPS device.

Link: http://lkml.kernel.org/r/20190702092251.24303-1-mlichvar@redhat.com
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Cc: Greg KH <greg@kroah.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 3a546ec10d904bb851801d716e2f53c7b47bf852..22a65ad4e46e6b187c885274aa3bfdb7ebcdb90c 100644 (file)
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -152,6 +152,14 @@ static long pps_cdev_ioctl(struct file *file,
                        pps->params.mode |= PPS_CANWAIT;
                pps->params.api_version = PPS_API_VERS;
 
+               /*
+                * Clear unused fields of pps_kparams to avoid leaking
+                * uninitialized data of the PPS_SETPARAMS caller via
+                * PPS_GETPARAMS
+                */
+               pps->params.assert_off_tu.flags = 0;
+               pps->params.clear_off_tu.flags = 0;
+
                spin_unlock_irq(&pps->lock);
 
                break;