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Subject[PATCH 4.19 199/276] rtc: xgene: fix possible race condition
Date
[ Upstream commit a652e00ee1233e251a337c28e18a1da59224e5ce ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/rtc/rtc-xgene.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-xgene.c b/drivers/rtc/rtc-xgene.c
index 153820876a820..2f741f455c30a 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;
}
--
2.20.1


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