net/x25: Fix x25_neigh refcnt leak when receiving frame

x25_lapb_receive_frame() invokes x25_get_neigh(), which returns a reference of the specified x25_neigh object to "nb" with increased refcnt. When x25_lapb_receive_frame() returns, local variable "nb" becomes invalid, so the refcount should be decreased to keep refcount balanced. The reference counting issue happens in one path of x25_lapb_receive_frame(). When pskb_may_pull() returns false, the function forgets to decrease the refcnt increased by x25_get_neigh(), causing a refcnt leak. Fix this issue by calling x25_neigh_put() when pskb_may_pull() returns false. Fixes: cb101ed ("x25: Handle undersized/fragmented skbs") Signed-off-by: Xiyu Yang <[email protected]> Signed-off-by: Xin Tan <[email protected]> Signed-off-by: David S. Miller <[email protected]>
dabrace · Apr 23, 2020 · f35d129 · f35d129
1 parent b4e0f9a
commit f35d129
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/net/x25/x25_dev.c b/net/x25/x25_dev.c
@@ -115,8 +115,10 @@ int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
 		goto drop;
 	}
 
-	if (!pskb_may_pull(skb, 1))
+	if (!pskb_may_pull(skb, 1)) {
+		x25_neigh_put(nb);
 		return 0;
+	}
 
 	switch (skb->data[0]) {