[PATCH v4] dma-buf: system_heap: Add a size check for allocation

[guangming.cao]

From: Guangming <Guangming.Cao@xxxxxxxxxxxx>

Add a size check for allocation since the allocation size should be
always less than the total DRAM size on system heap.
And it can prevent consuming too much time for invalid allocations.

Signed-off-by: Guangming <Guangming.Cao@xxxxxxxxxxxx>
---
 drivers/dma-buf/heaps/system_heap.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 23a7e74ef966..bd6f255620e2 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -347,6 +347,13 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
 	struct page *page, *tmp_page;
 	int i, ret = -ENOMEM;
 
+	/*
+	 * Size check. The "len" should be less than totalram since system_heap
+	 * memory is comes from system. Adding check here can prevent consuming
+	 * too much time for invalid allocations.
+	 */
+	if (len >> PAGE_SHIFT > totalram_pages())
+		return -EINVAL;
 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 	if (!buffer)
 		return ERR_PTR(-ENOMEM);
-- 
2.17.1