linux-kernel - [PATCH] clocksource: atmel-st: Variable sr in at91rm9200_timer

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Date:   Mon,  2 Sep 2019 15:29:46 -0700
From:   Yizhuo <yzhai003@....edu>
To:     unlisted-recipients:; (no To-header on input)
Cc:     csong@...ucr.edu, zhiyunq@...ucr.edu, Yizhuo <yzhai003@....edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] clocksource: atmel-st: Variable sr in at91rm9200_timer_interrupt() could be uninitialized

Inside function at91rm9200_timer_interrupt(), variable sr could
be uninitialized if regmap_read() fails. However, sr is used
to decide the control flow later in the if statement, which is
potentially unsafe. We could check the return value of
regmap_read() and print an error here.

Signed-off-by: Yizhuo <yzhai003@....edu>
---
 drivers/clocksource/timer-atmel-st.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-atmel-st.c b/drivers/clocksource/timer-atmel-st.c
index ab0aabfae5f0..061a3f27847e 100644
--- a/drivers/clocksource/timer-atmel-st.c
+++ b/drivers/clocksource/timer-atmel-st.c
@@ -48,8 +48,14 @@ static inline unsigned long read_CRTR(void)
 static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id)
 {
 	u32 sr;
+	int ret;
+
+	ret = regmap_read(regmap_st, AT91_ST_SR, &sr);
+	if (ret) {
+		pr_err("Fail to read AT91_ST_SR.\n");
+		return ret;
+	}
 
-	regmap_read(regmap_st, AT91_ST_SR, &sr);
 	sr &= irqmask;
 
 	/*
-- 
2.17.1