linux-kernel - [PATCH] mmc: core: Fix warning and undefined behavior in mmc voltage handling

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Date:   Tue, 16 Apr 2019 09:58:45 +0200
From:   Pavel Machek <pavel@....cz>
To:     ulf.hansson@...aro.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Subject: [PATCH] mmc: core: Fix warning and undefined behavior in mmc voltage
 handling


!voltage_ranges is tested for too late, allowing warning and undefined
behavior. Fix that.

Signed-off-by: Pavel Machek <pavel@....cz>

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 3a4402a..b3fa9c9 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -363,11 +363,11 @@ int mmc_of_parse_voltage(struct device_node *np, u32 *mask)
 	int num_ranges, i;
 
 	voltage_ranges = of_get_property(np, "voltage-ranges", &num_ranges);
-	num_ranges = num_ranges / sizeof(*voltage_ranges) / 2;
 	if (!voltage_ranges) {
 		pr_debug("%pOF: voltage-ranges unspecified\n", np);
 		return 0;
 	}
+	num_ranges = num_ranges / sizeof(*voltage_ranges) / 2;
 	if (!num_ranges) {
 		pr_err("%pOF: voltage-ranges empty\n", np);
 		return -EINVAL;

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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