rtc: xgene: fix possible race condition

The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler. This may lead to a NULL pointer
dereference.

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
struct before requesting the IRQ.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/rtc/rtc-xgene.c b/drivers/rtc/rtc-xgene.c
index 153820876a82..2f741f455c30 100644
--- a/drivers/rtc/rtc-xgene.c
+++ b/drivers/rtc/rtc-xgene.c
@@ -168,6 +168,10 @@ static int xgene_rtc_probe(struct platform_device *pdev)
         if (IS_ERR(pdata->csr_base))
                 return PTR_ERR(pdata->csr_base);
 
+        pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
+        if (IS_ERR(pdata->rtc))
+                return PTR_ERR(pdata->rtc);
+
         irq = platform_get_irq(pdev, 0);
         if (irq < 0) {
                 dev_err(&pdev->dev, "No IRQ resource\n");
@@ -198,15 +202,15 @@ static int xgene_rtc_probe(struct platform_device *pdev)
                 return ret;
         }
 
-        pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
-                                         &xgene_rtc_ops, THIS_MODULE);
-        if (IS_ERR(pdata->rtc)) {
-                clk_disable_unprepare(pdata->clk);
-                return PTR_ERR(pdata->rtc);
-        }
-
         /* HW does not support update faster than 1 seconds */
         pdata->rtc->uie_unsupported = 1;
+        pdata->rtc->ops = &xgene_rtc_ops;
+
+        ret = rtc_register_device(pdata->rtc);
+        if (ret) {
+                clk_disable_unprepare(pdata->clk);
+                return ret;
+        }
 
         return 0;
 }