1 files changed, 37 insertions, 13 deletions

diff --git a/net/mctp/route.c b/net/mctp/route.c
index 597e9cf5aa64..d9c8e5a5f9ce 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -313,8 +313,10 @@ static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev)
 
 	key = flow->key;
 
-	if (WARN_ON(key->dev && key->dev != dev))
+	if (key->dev) {
+		WARN_ON(key->dev != dev);
 		return;
+	}
 
 	mctp_dev_set_key(dev, key);
 }
@@ -332,8 +334,14 @@ static int mctp_frag_queue(struct mctp_sk_key *key, struct sk_buff *skb)
 		& MCTP_HDR_SEQ_MASK;
 
 	if (!key->reasm_head) {
-		key->reasm_head = skb;
-		key->reasm_tailp = &(skb_shinfo(skb)->frag_list);
+		/* Since we're manipulating the shared frag_list, ensure it isn't
+		 * shared with any other SKBs.
+		 */
+		key->reasm_head = skb_unshare(skb, GFP_ATOMIC);
+		if (!key->reasm_head)
+			return -ENOMEM;
+
+		key->reasm_tailp = &(skb_shinfo(key->reasm_head)->frag_list);
 		key->last_seq = this_seq;
 		return 0;
 	}
@@ -374,8 +382,13 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 	msk = NULL;
 	rc = -EINVAL;
 
-	/* we may be receiving a locally-routed packet; drop source sk
-	 * accounting
+	/* We may be receiving a locally-routed packet; drop source sk
+	 * accounting.
+	 *
+	 * From here, we will either queue the skb - either to a frag_queue, or
+	 * to a receiving socket. When that succeeds, we clear the skb pointer;
+	 * a non-NULL skb on exit will be otherwise unowned, and hence
+	 * kfree_skb()-ed.
 	 */
 	skb_orphan(skb);
 
@@ -434,7 +447,9 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 		 * pending key.
 		 */
 		if (flags & MCTP_HDR_FLAG_EOM) {
-			sock_queue_rcv_skb(&msk->sk, skb);
+			rc = sock_queue_rcv_skb(&msk->sk, skb);
+			if (!rc)
+				skb = NULL;
 			if (key) {
 				/* we've hit a pending reassembly; not much we
 				 * can do but drop it
@@ -443,7 +458,6 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 						   MCTP_TRACE_KEY_REPLIED);
 				key = NULL;
 			}
-			rc = 0;
 			goto out_unlock;
 		}
 
@@ -470,8 +484,10 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 			 * this function.
 			 */
 			rc = mctp_key_add(key, msk);
-			if (!rc)
+			if (!rc) {
 				trace_mctp_key_acquire(key);
+				skb = NULL;
+			}
 
 			/* we don't need to release key->lock on exit, so
 			 * clean up here and suppress the unlock via
@@ -489,6 +505,8 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 				key = NULL;
 			} else {
 				rc = mctp_frag_queue(key, skb);
+				if (!rc)
+					skb = NULL;
 			}
 		}
 
@@ -503,12 +521,19 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 		else
 			rc = mctp_frag_queue(key, skb);
 
+		if (rc)
+			goto out_unlock;
+
+		/* we've queued; the queue owns the skb now */
+		skb = NULL;
+
 		/* end of message? deliver to socket, and we're done with
 		 * the reassembly/response key
 		 */
-		if (!rc && flags & MCTP_HDR_FLAG_EOM) {
-			sock_queue_rcv_skb(key->sk, key->reasm_head);
-			key->reasm_head = NULL;
+		if (flags & MCTP_HDR_FLAG_EOM) {
+			rc = sock_queue_rcv_skb(key->sk, key->reasm_head);
+			if (!rc)
+				key->reasm_head = NULL;
 			__mctp_key_done_in(key, net, f, MCTP_TRACE_KEY_REPLIED);
 			key = NULL;
 		}
@@ -527,8 +552,7 @@ out_unlock:
 	if (any_key)
 		mctp_key_unref(any_key);
 out:
-	if (rc)
-		kfree_skb(skb);
+	kfree_skb(skb);
 	return rc;
 }