linux-kernel - [PATCH -next] rtc: synqmp: uninitialized variable error

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Date:   Wed,  3 Aug 2022 07:01:17 +0530
From:   Sebin Sebastian <mailmesebin00@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     mailmesebin00@...il.com, Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-rtc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH -next] rtc: synqmp: uninitialized variable error

fract_tick is uninitialized and can lead to uninitialized read which can
result in any arbitrary value from previous computations. If the code
flow doesnt execute the `if (fract_offset > (tick_mult /
RTC_FR_MAX_TICKS)) { ` block, fract_tick is left uninitialized.
Initializing with zero fixes the issue.

Signed-off-by: Sebin Sebastian <mailmesebin00@...il.com>
---
 drivers/rtc/rtc-zynqmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index 1dd389b891fe..c9b85c838ebe 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -203,7 +203,7 @@ static int xlnx_rtc_set_offset(struct device *dev, long offset)
 	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 	unsigned long long rtc_ppb = RTC_PPB;
 	unsigned int tick_mult = do_div(rtc_ppb, xrtcdev->freq);
-	unsigned char fract_tick;
+	unsigned char fract_tick = 0;
 	unsigned int calibval;
 	short int  max_tick;
 	int fract_offset;
-- 
2.34.1