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From:   <guangming.cao@mediatek.com>
To:     <john.stultz@linaro.org>
CC:     <benjamin.gaignard@linaro.org>, <bo.song@mediatek.com>,
        <caoguangming34@gmail.com>, <christian.koenig@amd.com>,
        <dri-devel@lists.freedesktop.org>, <guangming.cao@mediatek.com>,
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        <mingyuan.ma@mediatek.com>, <sumit.semwal@linaro.org>,
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        Guangming <Guangming.Cao@mediatek.com>
Subject: [PATCH v5] dma-buf: system_heap: Add a size check for allocation
Date:   Thu, 20 Jan 2022 15:08:50 +0800
Message-ID: <20220120070850.95495-1-guangming.cao@mediatek.com>
In-Reply-To: <CALAqxLW5uEZCGHGk3rYoiOGzN5XMKb39JzoPB1iEX9k3UsiT-A@mail.gmail.com>
References: <CALAqxLW5uEZCGHGk3rYoiOGzN5XMKb39JzoPB1iEX9k3UsiT-A@mail.gmail.com>
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From: Guangming <Guangming.Cao@mediatek.com>

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

Signed-off-by: Guangming <Guangming.Cao@mediatek.com>
---
 drivers/dma-buf/heaps/system_heap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 23a7e74ef966..459dc18bc4a2 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -347,6 +347,14 @@ 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 comsuming
+	 * too much time for invalid allocations.
+	 */
+	if (len >> PAGE_SHIFT > totalram_pages())
+		return ERR_PTR(-EINVAL);
+
 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 	if (!buffer)
 		return ERR_PTR(-ENOMEM);
-- 
2.17.1