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

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 1ad5808..0f467a7 100644 (file)
--- 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>
@@ -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);
 }