[PATCH] drm/exynos: g2d: fix null pointer dereference

[Inki Dae]

This patch fixes a null pointer dereference issue incurred by
calling g2d_remove when exynos_drm_platform_probe is failed.

cmdlist_pool of g2d is allocated when g2d sub driver is probed.
So if exynos_drm_platform_probe is failed, the g2d sub driver is
not probed and the cmdlist_pool is still NULL.

This patch makes for g2d_remove function tries to free
the cmdlist_poll only in case that the cmdlist_poll is allocated.

Signed-off-by: Inki Dae <inki.dae at samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_g2d.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index df7a77d..6ff8599 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -302,9 +302,12 @@ static void g2d_fini_cmdlist(struct g2d_data *g2d)
 	struct exynos_drm_subdrv *subdrv = &g2d->subdrv;
 
 	kfree(g2d->cmdlist_node);
-	dma_free_attrs(subdrv->drm_dev->dev, G2D_CMDLIST_POOL_SIZE,
-			g2d->cmdlist_pool_virt,
-			g2d->cmdlist_pool, &g2d->cmdlist_dma_attrs);
+
+	if (g2d->cmdlist_pool_virt && g2d->cmdlist_pool) {
+		dma_free_attrs(subdrv->drm_dev->dev, G2D_CMDLIST_POOL_SIZE,
+				g2d->cmdlist_pool_virt,
+				g2d->cmdlist_pool, &g2d->cmdlist_dma_attrs);
+	}
 }
 
 static struct g2d_cmdlist_node *g2d_get_cmdlist(struct g2d_data *g2d)
-- 
1.7.9.5