linux-kernel - [PATCH] mt76: fix memcpy to potential null pointer on failed allocation

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Message-Id: <20171214101322.10178-1-colin.king@canonical.com>
Date:   Thu, 14 Dec 2017 10:13:22 +0000
From:   Colin King <colin.king@...onical.com>
To:     Kalle Valo <kvalo@...eaurora.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Lorenzo Bianconi <lorenzo.bianconi83@...il.com>,
        Felix Fietkau <nbd@....name>, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mt76: fix memcpy to potential null pointer on failed allocation

From: Colin Ian King <colin.king@...onical.com>

Currently if the allocation of skb fails and returns NULL then the
call to skb_put will cause a null pointer dereference. Fix this by
checking for a null skb and returning NULL.  Note that calls to
function mt76x2_mcu_msg_alloc don't directly check the null return
but instead pass the NULL pointer to mt76x2_mcu_msg_send which
checks for the NULL and returns ENOMEM in this case.

Detected by CoverityScan, CID#1462624 ("Dereference null return value")

Fixes: 7bc04215a66b ("mt76: add driver code for MT76x2e")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c b/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c
index d45737ee1412..15820b11f9db 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2_mcu.c
@@ -45,6 +45,8 @@ static struct sk_buff *mt76x2_mcu_msg_alloc(const void *data, int len)
 	struct sk_buff *skb;
 
 	skb = alloc_skb(len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
 	memcpy(skb_put(skb, len), data, len);
 
 	return skb;
-- 
2.14.1