[PATCH 4.9 59/80] remoteproc: Fix wrong rvring index computation

[Greg Kroah-Hartman]

From: Clement Leger <cleger@xxxxxxxxx>

commit 00a0eec59ddbb1ce966b19097d8a8d2f777e726a upstream.

Index of rvring is computed using pointer arithmetic. However, since
rvring->rvdev->vring is the base of the vring array, computation
of rvring idx should be reversed. It previously lead to writing at negative
indices in the resource table.

Signed-off-by: Clement Leger <cleger@xxxxxxxxx>
Link: https://lore.kernel.org/r/20191004073736.8327-1-cleger@xxxxxxxxx
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Cc: Doug Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/remoteproc/remoteproc_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -284,7 +284,7 @@ void rproc_free_vring(struct rproc_vring
 {
 	int size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));
 	struct rproc *rproc = rvring->rvdev->rproc;
-	int idx = rvring->rvdev->vring - rvring;
+	int idx = rvring - rvring->rvdev->vring;
 	struct fw_rsc_vdev *rsc;
 
 	dma_free_coherent(rproc->dev.parent, size, rvring->va, rvring->dma);