linux-kernel - [PATCH 3.16 072/134] HSI: ssi_protocol: double free in ssip_pn

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Date:   Fri, 18 Aug 2017 14:13:20 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Dan Carpenter" <dan.carpenter@...cle.com>,
        "Sebastian Reichel" <sre@...nel.org>
Subject: [PATCH 3.16 072/134] HSI: ssi_protocol: double free in ssip_pn_xmit()

3.16.47-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 3026050179a3a9a6f5c892c414b5e36ecf092081 upstream.

If skb_pad() fails then it frees skb and we don't need to free it again
at the end of the function.

Fixes: dc7bf5d7 ("HSI: Introduce driver for SSI Protocol")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Sebastian Reichel <sre@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/hsi/clients/ssi_protocol.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/hsi/clients/ssi_protocol.c
+++ b/drivers/hsi/clients/ssi_protocol.c
@@ -976,7 +976,7 @@ static int ssip_pn_xmit(struct sk_buff *
 		goto drop;
 	/* Pad to 32-bits - FIXME: Revisit*/
 	if ((skb->len & 3) && skb_pad(skb, 4 - (skb->len & 3)))
-		goto drop;
+		goto inc_dropped;
 
 	/*
 	 * Modem sends Phonet messages over SSI with its own endianess...
@@ -1028,8 +1028,9 @@ static int ssip_pn_xmit(struct sk_buff *
 drop2:
 	hsi_free_msg(msg);
 drop:
-	dev->stats.tx_dropped++;
 	dev_kfree_skb(skb);
+inc_dropped:
+	dev->stats.tx_dropped++;
 
 	return 0;
 }