From: Miaohe Lin <linmiaohe@huawei.com>
Date: Mon, 10 Aug 2020 08:16:58 -0400
Subject: net: Fix potential memory leak in proto_register()
Git-commit: 0f5907af39137f8183ed536aaa00f322d7365130
Patch-mainline: 5.9-rc1
References: networking-stable-20_08_15

If we failed to assign proto idx, we free the twsk_slab_name but forget to
free the twsk_slab. Add a helper function tw_prot_cleanup() to free these
together and also use this helper function in proto_unregister().

Fixes: b45ce32135d1 ("sock: fix potential memory leak in proto_register()")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/core/sock.c |   25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3341,6 +3341,16 @@ static void sock_inuse_add(struct net *n
 }
 #endif
 
+static void tw_prot_cleanup(struct timewait_sock_ops *twsk_prot)
+{
+	if (!twsk_prot)
+		return;
+	kfree(twsk_prot->twsk_slab_name);
+	twsk_prot->twsk_slab_name = NULL;
+	kmem_cache_destroy(twsk_prot->twsk_slab);
+	twsk_prot->twsk_slab = NULL;
+}
+
 static void req_prot_cleanup(struct request_sock_ops *rsk_prot)
 {
 	if (!rsk_prot)
@@ -3411,7 +3421,7 @@ int proto_register(struct proto *prot, i
 						  prot->slab_flags,
 						  NULL);
 			if (prot->twsk_prot->twsk_slab == NULL)
-				goto out_free_timewait_sock_slab_name;
+				goto out_free_timewait_sock_slab;
 		}
 	}
 
@@ -3419,15 +3429,15 @@ int proto_register(struct proto *prot, i
 	ret = assign_proto_idx(prot);
 	if (ret) {
 		mutex_unlock(&proto_list_mutex);
-		goto out_free_timewait_sock_slab_name;
+		goto out_free_timewait_sock_slab;
 	}
 	list_add(&prot->node, &proto_list);
 	mutex_unlock(&proto_list_mutex);
 	return ret;
 
-out_free_timewait_sock_slab_name:
+out_free_timewait_sock_slab:
 	if (alloc_slab && prot->twsk_prot)
-		kfree(prot->twsk_prot->twsk_slab_name);
+		tw_prot_cleanup(prot->twsk_prot);
 out_free_request_sock_slab:
 	if (alloc_slab) {
 		req_prot_cleanup(prot->rsk_prot);
@@ -3451,12 +3461,7 @@ void proto_unregister(struct proto *prot
 	prot->slab = NULL;
 
 	req_prot_cleanup(prot->rsk_prot);
-
-	if (prot->twsk_prot != NULL && prot->twsk_prot->twsk_slab != NULL) {
-		kmem_cache_destroy(prot->twsk_prot->twsk_slab);
-		kfree(prot->twsk_prot->twsk_slab_name);
-		prot->twsk_prot->twsk_slab = NULL;
-	}
+	tw_prot_cleanup(prot->twsk_prot);
 }
 EXPORT_SYMBOL(proto_unregister);