[PATCH] drm/tegra: Check whether page belongs to BO in tegra_bo_kmap()

[Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

This fixes an OOPS in case of out-of-bounds accessing of a kmap'ed commands
buffer CMA while patching relocations in do_relocs().

Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/gpu/drm/tegra/gem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
index 424569b53e57..b76d7ac75696 100644
--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -74,6 +74,9 @@ static void *tegra_bo_kmap(struct host1x_bo *bo, unsigned int page)
 {
 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
 
+	if (page * PAGE_SIZE > obj->gem.size)
+		return NULL;
+
 	if (obj->vaddr)
 		return obj->vaddr + page * PAGE_SIZE;
 	else if (obj->gem.import_attach)
-- 
2.13.0