[PATCH 4.9 16/72] drm/sti: sti_vtg: Handle return NULL error from devm_ioremap_nocache

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arvind Yadav <arvind.yadav...@gmail.com>


[ Upstream commit 1ae0d5af347df224a6e76334683f13a96d915a44 ]

Here, If devm_ioremap_nocache will fail. It will return NULL.
Kernel can run into a NULL-pointer dereference. This error check
will avoid NULL pointer dereference.

Signed-off-by: Arvind Yadav <arvind.yadav...@gmail.com>
Acked-by: Vincent Abriou <vincent.abr...@st.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/gpu/drm/sti/sti_vtg.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/sti/sti_vtg.c
+++ b/drivers/gpu/drm/sti/sti_vtg.c
@@ -429,6 +429,10 @@ static int vtg_probe(struct platform_dev
                return -ENOMEM;
        }
        vtg->regs = devm_ioremap_nocache(dev, res->start, resource_size(res));
+       if (!vtg->regs) {
+               DRM_ERROR("failed to remap I/O memory\n");
+               return -ENOMEM;
+       }
 
        np = of_parse_phandle(pdev->dev.of_node, "st,slave", 0);
        if (np) {