linux-kernel - RE: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation

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Date:   Thu, 13 Jan 2022 12:57:51 +0000
From:   "Ruhl, Michael J" <michael.j.ruhl@...el.com>
To:     "guangming.cao@...iatek.com" <guangming.cao@...iatek.com>,
        "sumit.semwal@...aro.org" <sumit.semwal@...aro.org>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "mingyuan.ma@...iatek.com" <mingyuan.ma@...iatek.com>,
        "wsd_upstream@...iatek.com" <wsd_upstream@...iatek.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
        "yf.wang@...iatek.com" <yf.wang@...iatek.com>,
        "libo.kang@...iatek.com" <libo.kang@...iatek.com>,
        "benjamin.gaignard@...aro.org" <benjamin.gaignard@...aro.org>,
        "bo.song@...iatek.com" <bo.song@...iatek.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "lmark@...eaurora.org" <lmark@...eaurora.org>,
        "labbott@...hat.com" <labbott@...hat.com>,
        "christian.koenig@....com" <christian.koenig@....com>,
        "jianjiao.zeng@...iatek.com" <jianjiao.zeng@...iatek.com>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>
Subject: RE: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation


>-----Original Message-----
>From: dri-devel <dri-devel-bounces@...ts.freedesktop.org> On Behalf Of
>guangming.cao@...iatek.com
>Sent: Thursday, January 13, 2022 7:34 AM
>To: sumit.semwal@...aro.org
>Cc: linux-arm-kernel@...ts.infradead.org; mingyuan.ma@...iatek.com;
>Guangming <Guangming.Cao@...iatek.com>;
>wsd_upstream@...iatek.com; linux-kernel@...r.kernel.org; dri-
>devel@...ts.freedesktop.org; linaro-mm-sig@...ts.linaro.org;
>yf.wang@...iatek.com; libo.kang@...iatek.com;
>benjamin.gaignard@...aro.org; bo.song@...iatek.com;
>matthias.bgg@...il.com; linux-mediatek@...ts.infradead.org;
>lmark@...eaurora.org; labbott@...hat.com; christian.koenig@....com;
>jianjiao.zeng@...iatek.com; linux-media@...r.kernel.org
>Subject: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation
>
>From: Guangming <Guangming.Cao@...iatek.com>
>
>Add a size check for allocation since the allocation size is
>always less than the total DRAM size.
>
>Without this check, once the invalid size allocation runs on a process that
>can't be killed by OOM flow(such as "gralloc" on Android devices), it will
>cause a kernel exception, and to make matters worse, we can't find who are
>using
>so many memory with "dma_buf_debug_show" since the relevant dma-buf
>hasn't exported.
>
>To make OOM issue easier, maybe need dma-buf framework to dump the
>buffer size
>under allocating in "dma_buf_debug_show".
>
>Signed-off-by: Guangming <Guangming.Cao@...iatek.com>
>Signed-off-by: jianjiao zeng <jianjiao.zeng@...iatek.com>
>---
>v3: 1. update patch, use right shift to replace division.
>    2. update patch, add reason in code and commit message.
>v2: 1. update size limitation as total_dram page size.
>    2. update commit message
>---
> drivers/dma-buf/dma-heap.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
>diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
>index 56bf5ad01ad5..1fd382712584 100644
>--- a/drivers/dma-buf/dma-heap.c
>+++ b/drivers/dma-buf/dma-heap.c
>@@ -55,6 +55,16 @@ static int dma_heap_buffer_alloc(struct dma_heap
>*heap, size_t len,
> 	struct dma_buf *dmabuf;
> 	int fd;
>
>+	/*
>+	 * Invalid size check. The "len" should be less than totalram.
>+	 *
>+	 * Without this check, once the invalid size allocation runs on a process
>that
>+	 * can't be killed by OOM flow(such as "gralloc" on Android devices), it
>will
>+	 * cause a kernel exception, and to make matters worse, we can't find
>who are using
>+	 * so many memory with "dma_buf_debug_show" since the relevant
>dma-buf hasn't exported.
>+	 */
>+	if (len >> PAGE_SHIFT > totalram_pages())

If your "heap" is from cma, is this still a valid check?

M

>+		return -EINVAL;
> 	/*
> 	 * Allocations from all heaps have to begin
> 	 * and end on page boundaries.
>--
>2.17.1