On Mon, Nov 19, 2018 at 03:07:37PM +0100, Greg Kroah-Hartman wrote:
>
> The patch below does not apply to the 4.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
This one also depends on
36156f9241cb ("of: add helper to lookup compatible child node")
Johan
> ------------------ original commit in Linus's tree ------------------
>
> From f9a7082327e26f54067a49cac2316d31e0cc8ba7 Mon Sep 17 00:00:00 2001
> From: Johan Hovold <johan@xxxxxxxxxx>
> Date: Mon, 27 Aug 2018 10:21:47 +0200
> Subject: [PATCH] drm/msm: fix OF child-node lookup
>
> Use the new of_get_compatible_child() helper to lookup the legacy
> pwrlevels child node instead of using of_find_compatible_node(), which
> searches the entire tree from a given start node and thus can return an
> unrelated (i.e. non-child) node.
>
> This also addresses a potential use-after-free (e.g. after probe
> deferral) as the tree-wide helper drops a reference to its first
> argument (i.e. the probed device's node).
>
> While at it, also fix the related child-node reference leak.
>
> Fixes: e2af8b6b0ca1 ("drm/msm: gpu: Use OPP tables if we can")
> Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.12
> Cc: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
> Cc: Rob Clark <robdclark@xxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index da1363a0c54d..93d70f4a2154 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -633,8 +633,7 @@ static int adreno_get_legacy_pwrlevels(struct device *dev)
> struct device_node *child, *node;
> int ret;
>
> - node = of_find_compatible_node(dev->of_node, NULL,
> - "qcom,gpu-pwrlevels");
> + node = of_get_compatible_child(dev->of_node, "qcom,gpu-pwrlevels");
> if (!node) {
> dev_err(dev, "Could not find the GPU powerlevels\n");
> return -ENXIO;
> @@ -655,6 +654,8 @@ static int adreno_get_legacy_pwrlevels(struct device *dev)
> dev_pm_opp_add(dev, val, 0);
> }
>
> + of_node_put(node);
> +
> return 0;
> }
>
>
