netdev - [PATCH net 1/3] net: dsa: rtl4_a: Pad using __skb_put

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Date:   Mon,  1 Mar 2021 14:32:39 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
        DENG Qingfang <dqfext@...il.com>,
        Mauri Sandberg <sandberg@...lfence.com>
Subject: [PATCH net 1/3] net: dsa: rtl4_a: Pad using __skb_put_padto()

The eth_skb_pad() function will cause a double free
on failure since dsa_slave_xmit() will try to free
the frame if we return NULL. Fix this by using
__skb_put_padto() instead.

Fixes: 86dd9868b878 ("net: dsa: tag_rtl4_a: Support also egress tags")
Reported-by: DENG Qingfang <dqfext@...il.com>
Cc: Mauri Sandberg <sandberg@...lfence.com>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
 net/dsa/tag_rtl4_a.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/dsa/tag_rtl4_a.c b/net/dsa/tag_rtl4_a.c
index c17d39b4a1a0..804d756dd80a 100644
--- a/net/dsa/tag_rtl4_a.c
+++ b/net/dsa/tag_rtl4_a.c
@@ -40,7 +40,7 @@ static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb,
 	u16 out;
 
 	/* Pad out to at least 60 bytes */
-	if (unlikely(eth_skb_pad(skb)))
+	if (__skb_put_padto(skb, ETH_ZLEN, false))
 		return NULL;
 	if (skb_cow_head(skb, RTL4_A_HDR_LEN) < 0)
 		return NULL;
-- 
2.29.2