1 files changed, 60 insertions, 47 deletions

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index b6c45dccba3d..f48e5857210f 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -416,26 +416,31 @@ bool tipc_msg_bundle(struct sk_buff *skb, struct tipc_msg *msg, u32 mtu)
  */
 bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
 {
-	struct tipc_msg *msg;
-	int imsz, offset;
+	struct tipc_msg *hdr, *ihdr;
+	int imsz;
 
 	*iskb = NULL;
 	if (unlikely(skb_linearize(skb)))
 		goto none;
 
-	msg = buf_msg(skb);
-	offset = msg_hdr_sz(msg) + *pos;
-	if (unlikely(offset > (msg_size(msg) - MIN_H_SIZE)))
+	hdr = buf_msg(skb);
+	if (unlikely(*pos > (msg_data_sz(hdr) - MIN_H_SIZE)))
 		goto none;
 
-	*iskb = skb_clone(skb, GFP_ATOMIC);
-	if (unlikely(!*iskb))
+	ihdr = (struct tipc_msg *)(msg_data(hdr) + *pos);
+	imsz = msg_size(ihdr);
+
+	if ((*pos + imsz) > msg_data_sz(hdr))
 		goto none;
-	skb_pull(*iskb, offset);
-	imsz = msg_size(buf_msg(*iskb));
-	skb_trim(*iskb, imsz);
+
+	*iskb = tipc_buf_acquire(imsz, GFP_ATOMIC);
+	if (!*iskb)
+		goto none;
+
+	skb_copy_to_linear_data(*iskb, ihdr, imsz);
 	if (unlikely(!tipc_msg_validate(iskb)))
 		goto none;
+
 	*pos += align(imsz);
 	return true;
 none:
@@ -494,60 +499,56 @@ bool tipc_msg_make_bundle(struct sk_buff **skb,  struct tipc_msg *msg,
 /**
  * tipc_msg_reverse(): swap source and destination addresses and add error code
  * @own_node: originating node id for reversed message
- * @skb:  buffer containing message to be reversed; may be replaced.
+ * @skb:  buffer containing message to be reversed; will be consumed
  * @err:  error code to be set in message, if any
- * Consumes buffer at failure
+ * Replaces consumed buffer with new one when successful
  * Returns true if success, otherwise false
  */
 bool tipc_msg_reverse(u32 own_node,  struct sk_buff **skb, int err)
 {
 	struct sk_buff *_skb = *skb;
-	struct tipc_msg *hdr;
-	struct tipc_msg ohdr;
-	int dlen;
+	struct tipc_msg *_hdr, *hdr;
+	int hlen, dlen;
 
 	if (skb_linearize(_skb))
 		goto exit;
-	hdr = buf_msg(_skb);
-	dlen = min_t(uint, msg_data_sz(hdr), MAX_FORWARD_SIZE);
-	if (msg_dest_droppable(hdr))
+	_hdr = buf_msg(_skb);
+	dlen = min_t(uint, msg_data_sz(_hdr), MAX_FORWARD_SIZE);
+	hlen = msg_hdr_sz(_hdr);
+
+	if (msg_dest_droppable(_hdr))
 		goto exit;
-	if (msg_errcode(hdr))
+	if (msg_errcode(_hdr))
 		goto exit;
 
-	/* Take a copy of original header before altering message */
-	memcpy(&ohdr, hdr, msg_hdr_sz(hdr));
+	/* Never return SHORT header */
+	if (hlen == SHORT_H_SIZE)
+		hlen = BASIC_H_SIZE;
 
-	/* Never return SHORT header; expand by replacing buffer if necessary */
-	if (msg_short(hdr)) {
-		*skb = tipc_buf_acquire(BASIC_H_SIZE + dlen, GFP_ATOMIC);
-		if (!*skb)
-			goto exit;
-		memcpy((*skb)->data + BASIC_H_SIZE, msg_data(hdr), dlen);
-		kfree_skb(_skb);
-		_skb = *skb;
-		hdr = buf_msg(_skb);
-		memcpy(hdr, &ohdr, BASIC_H_SIZE);
-		msg_set_hdr_sz(hdr, BASIC_H_SIZE);
-	}
+	/* Don't return data along with SYN+, - sender has a clone */
+	if (msg_is_syn(_hdr) && err == TIPC_ERR_OVERLOAD)
+		dlen = 0;
 
-	if (skb_cloned(_skb) &&
-	    pskb_expand_head(_skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC))
+	/* Allocate new buffer to return */
+	*skb = tipc_buf_acquire(hlen + dlen, GFP_ATOMIC);
+	if (!*skb)
 		goto exit;
+	memcpy((*skb)->data, _skb->data, msg_hdr_sz(_hdr));
+	memcpy((*skb)->data + hlen, msg_data(_hdr), dlen);
 
-	/* reassign after skb header modifications */
-	hdr = buf_msg(_skb);
-	/* Now reverse the concerned fields */
+	/* Build reverse header in new buffer */
+	hdr = buf_msg(*skb);
+	msg_set_hdr_sz(hdr, hlen);
 	msg_set_errcode(hdr, err);
 	msg_set_non_seq(hdr, 0);
-	msg_set_origport(hdr, msg_destport(&ohdr));
-	msg_set_destport(hdr, msg_origport(&ohdr));
-	msg_set_destnode(hdr, msg_prevnode(&ohdr));
+	msg_set_origport(hdr, msg_destport(_hdr));
+	msg_set_destport(hdr, msg_origport(_hdr));
+	msg_set_destnode(hdr, msg_prevnode(_hdr));
 	msg_set_prevnode(hdr, own_node);
 	msg_set_orignode(hdr, own_node);
-	msg_set_size(hdr, msg_hdr_sz(hdr) + dlen);
-	skb_trim(_skb, msg_size(hdr));
+	msg_set_size(hdr, hlen + dlen);
 	skb_orphan(_skb);
+	kfree_skb(_skb);
 	return true;
 exit:
 	kfree_skb(_skb);
@@ -555,6 +556,22 @@ exit:
 	return false;
 }
 
+bool tipc_msg_skb_clone(struct sk_buff_head *msg, struct sk_buff_head *cpy)
+{
+	struct sk_buff *skb, *_skb;
+
+	skb_queue_walk(msg, skb) {
+		_skb = skb_clone(skb, GFP_ATOMIC);
+		if (!_skb) {
+			__skb_queue_purge(cpy);
+			pr_err_ratelimited("Failed to clone buffer chain\n");
+			return false;
+		}
+		__skb_queue_tail(cpy, _skb);
+	}
+	return true;
+}
+
 /**
  * tipc_msg_lookup_dest(): try to find new destination for named message
  * @skb: the buffer containing the message.
@@ -595,10 +612,6 @@ bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
 	if (!skb_cloned(skb))
 		return true;
 
-	/* Unclone buffer in case it was bundled */
-	if (pskb_expand_head(skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC))
-		return false;
-
 	return true;
 }