slimbus: qcom: fix potential NULL dereference in qcom_slim_prg_slew()

platform_get_resource_byname() may fail and in this case a NULL
dereference will occur.

Fix it to use devm_platform_ioremap_resource_byname() instead of calling
platform_get_resource_byname() and devm_ioremap().

This is detected by Coccinelle semantic patch.

@@
expression pdev, res, n, t, e, e1, e2;
@@

res = \(platform_get_resource\|platform_get_resource_byname\)(pdev, t,
n);
+ if (!res)
+   return -EINVAL;
... when != res == NULL
e = devm_ioremap(e1, res->start, e2);

Fixes: ad7fcbc308b0 ("slimbus: qcom: Add Qualcomm Slimbus controller driver")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Link: https://lore.kernel.org/r/1607392473-20610-1-git-send-email-zhangchangzhong@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/slimbus/qcom-ctrl.c b/drivers/slimbus/qcom-ctrl.c
index 4aad256..f04b961 100644 (file)
--- a/drivers/slimbus/qcom-ctrl.c
+++ b/drivers/slimbus/qcom-ctrl.c
@@ -472,15 +472,10 @@ static void qcom_slim_rxwq(struct work_struct *work)
 static void qcom_slim_prg_slew(struct platform_device *pdev,
                                struct qcom_slim_ctrl *ctrl)
 {
-       struct resource *slew_mem;
-
        if (!ctrl->slew_reg) {
                /* SLEW RATE register for this SLIMbus */
-               slew_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM,
-                               "slew");
-               ctrl->slew_reg = devm_ioremap(&pdev->dev, slew_mem->start,
-                               resource_size(slew_mem));
-               if (!ctrl->slew_reg)
+               ctrl->slew_reg = devm_platform_ioremap_resource_byname(pdev, "slew");
+               if (IS_ERR(ctrl->slew_reg))
                        return;
        }