[PATCH RESEND] drm/mediatek: Add 0 size check to mtk_drm_gem_obj

[Justin Green]

Add a check to mtk_drm_gem_init if we attempt to allocate a GEM object
of 0 bytes. Currently, no such check exists and the kernel will panic if
a userspace application attempts to allocate a 0x0 GBM buffer.

Tested by attempting to allocate a 0x0 GBM buffer on an MT8188 and
verifying that we now return EINVAL.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
Signed-off-by: Justin green <greenjustin at chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_gem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index 4f2e3feabc0f..ee49367b6138 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -38,6 +38,9 @@ static struct mtk_drm_gem_obj *mtk_drm_gem_init(struct drm_device *dev,
 
 	size = round_up(size, PAGE_SIZE);
 
+        if (size == 0)
+		return ERR_PTR(-EINVAL);
+
 	mtk_gem_obj = kzalloc(sizeof(*mtk_gem_obj), GFP_KERNEL);
 	if (!mtk_gem_obj)
 		return ERR_PTR(-ENOMEM);
-- 
2.44.0.278.ge034bb2e1d-goog