linux-kernel - [PATCH] hwrng: fix division by zero in ks_sa_rng

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Message-ID: <20250919132002.180874-1-nm@ti.com>
Date: Fri, 19 Sep 2025 08:20:02 -0500
From: Nishanth Menon <nm@...com>
To: Uwe Kleine-König <u.kleine-koenig@...libre.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Olivia Mackall <olivia@...enic.com>
CC: Alexander Sverdlin <alexander.sverdlin@...ia.com>,
        Alexander Sverdlin
	<alexander.sverdlin@...il.com>,
        <linux-kernel@...r.kernel.org>, <linux-crypto@...r.kernel.org>,
        Nishanth Menon <nm@...com>
Subject: [PATCH] hwrng: fix division by zero in ks_sa_rng_init

Fix division by zero in ks_sa_rng_init caused by missing clock
pointer initialization. The clk_get_rate() call is performed on
an uninitialized clk pointer, resulting in division by zero when
calculating delay values.

Add clock initialization code before using the clock.

Fixes: 6d01d8511dce ("hwrng: ks-sa - Add minimum sleep time before ready-polling")
Signed-off-by: Nishanth Menon <nm@...com>

 drivers/char/hw_random/ks-sa-rng.c | 7 +++++++
 1 file changed, 7 insertions(+)
---

Noticed this when looking at kci logs:
https://dashboard.kernelci.org/log-viewer?itemId=ti%3A0af42187f4b24261b0c102f0&org=ti&type=test&url=http%3A%2F%2Ffiles.kernelci.org%2F%2Fti%2Fmainline%2Fmaster%2Fv6.17-rc6-43-g8b789f2b7602%2Farm%2Fmulti_v7_defconfig%2BCONFIG_EFI%3Dy%2BCONFIG_ARM_LPAE%3Dy%2Bdebug%2Bkselftest%2Btinyconfig%2Fgcc-12%2Fbaseline-nfs-boot.nfs-k2hk-evm.txt.gz

Fixed version boot:
https://gist.github.com/nmenon/0996e5f7bdbcd3b014cee9921a60d88c

 drivers/char/hw_random/ks-sa-rng.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/char/hw_random/ks-sa-rng.c b/drivers/char/hw_random/ks-sa-rng.c
index d8fd8a354482..9e408144a10c 100644
--- a/drivers/char/hw_random/ks-sa-rng.c
+++ b/drivers/char/hw_random/ks-sa-rng.c
@@ -231,6 +231,10 @@ static int ks_sa_rng_probe(struct platform_device *pdev)
 	if (IS_ERR(ks_sa_rng->regmap_cfg))
 		return dev_err_probe(dev, -EINVAL, "syscon_node_to_regmap failed\n");
 
+	ks_sa_rng->clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(ks_sa_rng->clk))
+		return dev_err_probe(dev, PTR_ERR(ks_sa_rng->clk), "Failed to get clock\n");
+
 	pm_runtime_enable(dev);
 	ret = pm_runtime_resume_and_get(dev);
 	if (ret < 0) {
-- 
2.47.0