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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Krzysztof Kozlowski <krzk@kernel.org>,
        Pankaj Dubey <pankaj.dubey@samsung.com>
Subject: [PATCH 5.10 550/663] soc: samsung: exynos-asv: handle reading revision register error
Date:   Mon,  1 Mar 2021 17:13:18 +0100
Message-Id: <20210301161209.082441585@linuxfoundation.org>
In-Reply-To: <20210301161141.760350206@linuxfoundation.org>
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From: Krzysztof Kozlowski <krzk@kernel.org>

commit 4561560dfb4f847a0b327d48bdd1f45bf1b6261f upstream.

If regmap_read() fails, the product_id local variable will contain
random value from the stack.  Do not try to parse such value and fail
the ASV driver probe.

Fixes: 5ea428595cc5 ("soc: samsung: Add Exynos Adaptive Supply Voltage driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Link: https://lore.kernel.org/r/20201207190517.262051-3-krzk@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/soc/samsung/exynos-asv.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/soc/samsung/exynos-asv.c
+++ b/drivers/soc/samsung/exynos-asv.c
@@ -129,7 +129,13 @@ static int exynos_asv_probe(struct platf
 		return PTR_ERR(asv->chipid_regmap);
 	}
 
-	regmap_read(asv->chipid_regmap, EXYNOS_CHIPID_REG_PRO_ID, &product_id);
+	ret = regmap_read(asv->chipid_regmap, EXYNOS_CHIPID_REG_PRO_ID,
+			  &product_id);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Cannot read revision from ChipID: %d\n",
+			ret);
+		return -ENODEV;
+	}
 
 	switch (product_id & EXYNOS_MASK) {
 	case 0xE5422000: