drm/msm: fix leak in failed get_pages

get_pages doesn't keep a reference of the pages allocated
when it fails later in the code path. This can lead to
a memory leak. Keep reference of the allocated pages so
that it can be freed when msm_gem_free_object gets called
later during cleanup.

Signed-off-by: Prakash Kamliya <[e-mail]>
Signed-off-by: Sharat Masetty <[e-mail]>
Signed-off-by: Rob Clark <[e-mail]>

drivers/gpu/drm/msm/msm_gem.c

···
 			return p;
 		}
 
+		msm_obj->pages = p;
+
 		msm_obj->sgt = drm_prime_pages_to_sg(p, npages);
 		if (IS_ERR(msm_obj->sgt)) {
-			dev_err(dev->dev, "failed to allocate sgt\n");
-			return ERR_CAST(msm_obj->sgt);
-		}
+			void *ptr = ERR_CAST(msm_obj->sgt);
 
-		msm_obj->pages = p;
+			dev_err(dev->dev, "failed to allocate sgt\n");
+			msm_obj->sgt = NULL;
+			return ptr;
+		}
 
 		/* For non-cached buffers, ensure the new pages are clean
 		 * because display controller, GPU, etc. are not coherent:
···
 		if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
 			dma_unmap_sg(obj->dev->dev, msm_obj->sgt->sgl,
 					msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
-		sg_free_table(msm_obj->sgt);
+
+		if (msm_obj->sgt)
+			sg_free_table(msm_obj->sgt);
+
 		kfree(msm_obj->sgt);
 
 		if (use_pages(obj))