linux-kernel - [PATCH 01/11] misc: fastrpc: Assert held reservation lock for dma-buf mmapping

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Date:   Thu, 24 Nov 2022 17:51:15 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org,
        Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 01/11] misc: fastrpc: Assert held reservation lock for dma-buf mmapping

From: Dmitry Osipenko <dmitry.osipenko@...labora.com>

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@...ll.ch>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/misc/fastrpc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 80811e852d8f..c6b9ddaa698b 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -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>
@@ -692,6 +693,8 @@ 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);
 }
-- 
2.25.1