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

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Message-ID: <20190412093434.GA24516@amd>
Date:   Fri, 12 Apr 2019 11:34:34 +0200
From:   Pavel Machek <pavel@....cz>
To:     ulf.hansson@...aro.org, kernel list <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...l.org>,
        Trivial patch monkey <trivial@...nel.org>
Subject: [PATCH] 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>

---

Plus I guess author should add parenthesis in the expression. a / b /
c is _not_ common idiom.

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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