linux-kernel - [patch] mdio_bus: NULL dereference on allocation error

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Message-ID: <20160112093435.GD29804@mwanda>
Date:	Tue, 12 Jan 2016 12:34:36 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Florian Fainelli <f.fainelli@...il.com>,
	Andrew Lunn <andrew@...n.ch>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch] mdio_bus: NULL dereference on allocation error

If bus = kzalloc() fails then we end up dereferencing bus when we do
"bus->irq[i] = PHY_POLL;".  The code is a little simpler if we reverse
the NULL check and return directly on failure.

Fixes: e7f4dc3536a4 ('mdio: Move allocation of interrupts into core')
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 0be7b3d..0cba64f 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -102,11 +102,12 @@ struct mii_bus *mdiobus_alloc_size(size_t size)
 		alloc_size = sizeof(*bus);
 
 	bus = kzalloc(alloc_size, GFP_KERNEL);
-	if (bus) {
-		bus->state = MDIOBUS_ALLOCATED;
-		if (size)
-			bus->priv = (void *)bus + aligned_size;
-	}
+	if (!bus)
+		return NULL;
+
+	bus->state = MDIOBUS_ALLOCATED;
+	if (size)
+		bus->priv = (void *)bus + aligned_size;
 
 	/* Initialise the interrupts to polling */
 	for (i = 0; i < PHY_MAX_ADDR; i++)