drm/gma500: fix memory disclosures due to uninitialized bytes

BugLink: https://bugs.launchpad.net/bugs/1858462

[ Upstream commit ec3b7b6e ]

"clock" may be copied to "best_clock". Initializing best_clock
is not sufficient. The fix initializes clock as well to avoid
memory disclosures and informaiton leaks.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20191018044150.1899-1-kjlu@umn.eduSigned-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/gpu/drm/gma500/oaktrail_crtc.c

@@ -139,6 +139,7 @@ static bool mrst_sdvo_find_best_pll(const struct gma_limit_t *limit,
 	s32 freq_error, min_error = 100000;
 
 	memset(best_clock, 0, sizeof(*best_clock));
+	memset(&clock, 0, sizeof(clock));
 
 	for (clock.m = limit->m.min; clock.m <= limit->m.max; clock.m++) {
 		for (clock.n = limit->n.min; clock.n <= limit->n.max;
@@ -195,6 +196,7 @@ static bool mrst_lvds_find_best_pll(const struct gma_limit_t *limit,
 	int err = target;
 
 	memset(best_clock, 0, sizeof(*best_clock));
+	memset(&clock, 0, sizeof(clock));
 
 	for (clock.m = limit->m.min; clock.m <= limit->m.max; clock.m++) {
 		for (clock.p1 = limit->p1.min; clock.p1 <= limit->p1.max;