Commit 265751a5 authored Nov 10, 2022 by Dmitry Osipenko

fastrpc: Assert held reservation lock for dma-buf mmapping

When userspace mmaps dma-buf's fd, the dma-buf reservation lock must be
held. Add locking sanity check to the dma-buf mmaping callback to ensure
that the locking assumption won't regress in the future.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221110201349.351294-7-dmitry.osipenko@collabora.com

parent 3a6ca181

drivers/misc/fastrpc.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		#include <linux/device.h>
		#include <linux/dma-buf.h>
		#include <linux/dma-mapping.h>
		#include <linux/dma-resv.h>
		#include <linux/idr.h>
		#include <linux/list.h>
		#include <linux/miscdevice.h>
		@@ -682,6 +683,8 @@ static int fastrpc_mmap(struct dma_buf *dmabuf,
		struct fastrpc_buf *buf = dmabuf->priv;
		size_t size = vma->vm_end - vma->vm_start;

		dma_resv_assert_held(dmabuf->resv);

		return dma_mmap_coherent(buf->dev, vma, buf->virt,
		FASTRPC_PHYS(buf->phys), size);
		}