Messages in this thread | | | Subject | Re: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation | From | Christian König <> | Date | Thu, 13 Jan 2022 14:05:24 +0100 |
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Am 13.01.22 um 14:00 schrieb Ruhl, Michael J: >> -----Original Message----- >> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of >> Ruhl, Michael J >> Sent: Thursday, January 13, 2022 7:58 AM >> To: guangming.cao@mediatek.com; sumit.semwal@linaro.org >> Cc: jianjiao.zeng@mediatek.com; lmark@codeaurora.org; >> wsd_upstream@mediatek.com; christian.koenig@amd.com; linux- >> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; >> yf.wang@mediatek.com; linaro-mm-sig@lists.linaro.org; linux- >> mediatek@lists.infradead.org; libo.kang@mediatek.com; >> benjamin.gaignard@linaro.org; bo.song@mediatek.com; >> matthias.bgg@gmail.com; labbott@redhat.com; >> mingyuan.ma@mediatek.com; linux-arm-kernel@lists.infradead.org; linux- >> media@vger.kernel.org >> Subject: RE: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation >> >> >>> -----Original Message----- >>> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of >>> guangming.cao@mediatek.com >>> Sent: Thursday, January 13, 2022 7:34 AM >>> To: sumit.semwal@linaro.org >>> Cc: linux-arm-kernel@lists.infradead.org; mingyuan.ma@mediatek.com; >>> Guangming <Guangming.Cao@mediatek.com>; >>> wsd_upstream@mediatek.com; linux-kernel@vger.kernel.org; dri- >>> devel@lists.freedesktop.org; linaro-mm-sig@lists.linaro.org; >>> yf.wang@mediatek.com; libo.kang@mediatek.com; >>> benjamin.gaignard@linaro.org; bo.song@mediatek.com; >>> matthias.bgg@gmail.com; linux-mediatek@lists.infradead.org; >>> lmark@codeaurora.org; labbott@redhat.com; christian.koenig@amd.com; >>> jianjiao.zeng@mediatek.com; linux-media@vger.kernel.org >>> Subject: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation >>> >>> From: Guangming <Guangming.Cao@mediatek.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@mediatek.com> >>> Signed-off-by: jianjiao zeng <jianjiao.zeng@mediatek.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? > And thinking a bit further, if I create a heap from something else (say device memory), > you will need to be able to figure out the maximum allowable check for the specific > heap. > > Maybe the heap needs a callback for max size?
Well we currently maintain a separate allocator and don't use dma-heap, but yes we have systems with 16GiB device and only 8GiB system memory so that check here is certainly not correct.
In general I would rather let the system run into -ENOMEM or -EINVAL from the allocator instead.
Regards, Christian.
> > m >> M >> >>> + return -EINVAL; >>> /* >>> * Allocations from all heaps have to begin >>> * and end on page boundaries. >>> -- >>> 2.17.1
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