drm/tegra: Avoid potential 32-bit integer overflow

BugLink: https://bugs.launchpad.net/bugs/2028408

[ Upstream commit 2429b3c ]

In tegra_sor_compute_config(), the 32-bit value mode->clock is
multiplied by 1000, and assigned to the u64 variable pclk. We can avoid
a potential 32-bit integer overflow by casting mode->clock to u64 before
we do the arithmetic and assignment.

Signed-off-by: Nur Hussein <hussein@unixcat.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: nurh

drivers/gpu/drm/tegra/sor.c

@@ -1153,7 +1153,7 @@ static int tegra_sor_compute_config(struct tegra_sor *sor,
 				    struct drm_dp_link *link)
 {
 	const u64 f = 100000, link_rate = link->rate * 1000;
-	const u64 pclk = mode->clock * 1000;
+	const u64 pclk = (u64)mode->clock * 1000;
 	u64 input, output, watermark, num;
 	struct tegra_sor_params params;
 	u32 num_syms_per_line;