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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, Jon Maloy <jon.maloy@ericsson.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.19 11/42] tipc: dont assume linear buffer when reading ancillary data
Date:   Wed, 21 Nov 2018 20:05:47 +0100
Message-Id: <20181121183148.469188747@linuxfoundation.org>
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References: <20181121183147.869199006@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

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

From: Jon Maloy <donmalo99@gmail.com>

[ Upstream commit 1c1274a56999fbdf9cf84e332b28448bb2d55221 ]

The code for reading ancillary data from a received buffer is assuming
the buffer is linear. To make this assumption true we have to linearize
the buffer before message data is read.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/tipc/socket.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1548,16 +1548,17 @@ static void tipc_sk_set_orig_addr(struct
 /**
  * tipc_sk_anc_data_recv - optionally capture ancillary data for received message
  * @m: descriptor for message info
- * @msg: received message header
+ * @skb: received message buffer
  * @tsk: TIPC port associated with message
  *
  * Note: Ancillary data is not captured if not requested by receiver.
  *
  * Returns 0 if successful, otherwise errno
  */
-static int tipc_sk_anc_data_recv(struct msghdr *m, struct tipc_msg *msg,
+static int tipc_sk_anc_data_recv(struct msghdr *m, struct sk_buff *skb,
 				 struct tipc_sock *tsk)
 {
+	struct tipc_msg *msg;
 	u32 anc_data[3];
 	u32 err;
 	u32 dest_type;
@@ -1566,6 +1567,7 @@ static int tipc_sk_anc_data_recv(struct
 
 	if (likely(m->msg_controllen == 0))
 		return 0;
+	msg = buf_msg(skb);
 
 	/* Optionally capture errored message object(s) */
 	err = msg ? msg_errcode(msg) : 0;
@@ -1576,6 +1578,9 @@ static int tipc_sk_anc_data_recv(struct
 		if (res)
 			return res;
 		if (anc_data[1]) {
+			if (skb_linearize(skb))
+				return -ENOMEM;
+			msg = buf_msg(skb);
 			res = put_cmsg(m, SOL_TIPC, TIPC_RETDATA, anc_data[1],
 				       msg_data(msg));
 			if (res)
@@ -1737,9 +1742,10 @@ static int tipc_recvmsg(struct socket *s
 
 	/* Collect msg meta data, including error code and rejected data */
 	tipc_sk_set_orig_addr(m, skb);
-	rc = tipc_sk_anc_data_recv(m, hdr, tsk);
+	rc = tipc_sk_anc_data_recv(m, skb, tsk);
 	if (unlikely(rc))
 		goto exit;
+	hdr = buf_msg(skb);
 
 	/* Capture data if non-error msg, otherwise just set return value */
 	if (likely(!err)) {
@@ -1849,9 +1855,10 @@ static int tipc_recvstream(struct socket
 		/* Collect msg meta data, incl. error code and rejected data */
 		if (!copied) {
 			tipc_sk_set_orig_addr(m, skb);
-			rc = tipc_sk_anc_data_recv(m, hdr, tsk);
+			rc = tipc_sk_anc_data_recv(m, skb, tsk);
 			if (rc)
 				break;
+			hdr = buf_msg(skb);
 		}
 
 		/* Copy data if msg ok, otherwise return error/partial data */