ion: carveout heap: zero buffers on free, fix memory leak

The carveout heap wasn't zeroing its buffers after use.
Create the sg_table during allocate instead of map_dma, to allow
using the sg_table during free, and call ion_heap_buffer_zero
during free. Also fixes a missing kfree when destroying the
table.

Signed-off-by: Colin Cross <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/android/ion/ion_carveout_heap.c

···
  *
  */
 #include <linux/spinlock.h>
-
+#include <linux/dma-mapping.h>
 #include <linux/err.h>
 #include <linux/genalloc.h>
 #include <linux/io.h>
···
 				  struct ion_buffer *buffer,
 				  ion_phys_addr_t *addr, size_t *len)
 {
-	*addr = buffer->priv_phys;
+	struct sg_table *table = buffer->priv_virt;
+	struct page *page = sg_page(table->sgl);
+	ion_phys_addr_t paddr = PFN_PHYS(page_to_pfn(page));
+
+	*addr = paddr;
 	*len = buffer->size;
 	return 0;
 }
···
 				      unsigned long size, unsigned long align,
 				      unsigned long flags)
 {
+	struct sg_table *table;
+	ion_phys_addr_t paddr;
+	int ret;
+
 	if (align > PAGE_SIZE)
 		return -EINVAL;
 
-	buffer->priv_phys = ion_carveout_allocate(heap, size, align);
-	return buffer->priv_phys == ION_CARVEOUT_ALLOCATE_FAIL ? -ENOMEM : 0;
+	table = kzalloc(sizeof(struct sg_table), GFP_KERNEL);
+	if (!table)
+		return -ENOMEM;
+	ret = sg_alloc_table(table, 1, GFP_KERNEL);
+	if (ret)
+		goto err_free;
+
+	paddr = ion_carveout_allocate(heap, size, align);
+	if (paddr == ION_CARVEOUT_ALLOCATE_FAIL) {
+		ret = -ENOMEM;
+		goto err_free_table;
+	}
+
+	sg_set_page(table->sgl, pfn_to_page(PFN_DOWN(paddr)), size, 0);
+	buffer->priv_virt = table;
+
+	return 0;
+
+err_free_table:
+	sg_free_table(table);
+err_free:
+	kfree(table);
+	return ret;
 }
 
 static void ion_carveout_heap_free(struct ion_buffer *buffer)
 {
 	struct ion_heap *heap = buffer->heap;
+	struct sg_table *table = buffer->priv_virt;
+	struct page *page = sg_page(table->sgl);
+	ion_phys_addr_t paddr = PFN_PHYS(page_to_pfn(page));
 
-	ion_carveout_free(heap, buffer->priv_phys, buffer->size);
-	buffer->priv_phys = ION_CARVEOUT_ALLOCATE_FAIL;
+	ion_heap_buffer_zero(buffer);
+
+	if (ion_buffer_cached(buffer))
+		dma_sync_sg_for_device(NULL, table->sgl, table->nents,
+							DMA_BIDIRECTIONAL);
+
+	ion_carveout_free(heap, paddr, buffer->size);
+	sg_free_table(table);
+	kfree(table);
 }
 
 static struct sg_table *ion_carveout_heap_map_dma(struct ion_heap *heap,
 						  struct ion_buffer *buffer)
 {
-	struct sg_table *table;
-	int ret;
-
-	table = kzalloc(sizeof(struct sg_table), GFP_KERNEL);
-	if (!table)
-		return ERR_PTR(-ENOMEM);
-	ret = sg_alloc_table(table, 1, GFP_KERNEL);
-	if (ret) {
-		kfree(table);
-		return ERR_PTR(ret);
-	}
-	sg_set_page(table->sgl, pfn_to_page(PFN_DOWN(buffer->priv_phys)),
-			buffer->size, 0);
-	return table;
+	return buffer->priv_virt;
 }
 
 static void ion_carveout_heap_unmap_dma(struct ion_heap *heap,
 					struct ion_buffer *buffer)
 {
-	sg_free_table(buffer->sg_table);
+	return;
 }
 
 static struct ion_heap_ops carveout_heap_ops = {
···
 		     -1);
 	carveout_heap->heap.ops = &carveout_heap_ops;
 	carveout_heap->heap.type = ION_HEAP_TYPE_CARVEOUT;
+	carveout_heap->heap.flags = ION_HEAP_FLAG_DEFER_FREE;
 
 	return &carveout_heap->heap;
 }