i2c: mux: reg: check return value after calling platform_get_resource()

[ Upstream commit 2d47b79d2bd39cc6369eccf94a06568d84c906ae ]

It will cause null-ptr-deref in resource_size(), if platform_get_resource()
returns NULL, move calling resource_size() after devm_ioremap_resource() that
will check 'res' to avoid null-ptr-deref.
And use devm_platform_get_and_ioremap_resource() to simplify code.

Fixes: b3fdd32799d8 ("i2c: mux: Add register-based mux i2c-mux-reg")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/i2c/muxes/i2c-mux-reg.c b/drivers/i2c/muxes/i2c-mux-reg.c
index 0e0679f..30a6de1 100644 (file)
--- a/drivers/i2c/muxes/i2c-mux-reg.c
+++ b/drivers/i2c/muxes/i2c-mux-reg.c
@@ -183,13 +183,12 @@ static int i2c_mux_reg_probe(struct platform_device *pdev)
        if (!mux->data.reg) {
                dev_info(&pdev->dev,
                        "Register not set, using platform resource\n");
-               res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-               mux->data.reg_size = resource_size(res);
-               mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
+               mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
                if (IS_ERR(mux->data.reg)) {
                        ret = PTR_ERR(mux->data.reg);
                        goto err_put_parent;
                }
+               mux->data.reg_size = resource_size(res);
        }
 
        if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&