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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Sebastian Reichel <sre@kernel.org>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 33/97] HSI: ssi_protocol: double free in ssip_pn_xmit()
Date:   Fri, 23 Mar 2018 10:54:20 +0100
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

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


[ Upstream commit 3026050179a3a9a6f5c892c414b5e36ecf092081 ]

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@oracle.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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;
 }