[PATCH 5.10 550/663] soc: samsung: exynos-asv: handle reading revision register error

[Greg Kroah-Hartman]

From: Krzysztof Kozlowski <krzk@xxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
Reviewed-by: Pankaj Dubey <pankaj.dubey@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201207190517.262051-3-krzk@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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: