From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Wed, 10 Jun 2020 19:29:16 +0200
Subject: netfilter: nf_tables: hook list memleak in flowtable deletion
Patch-mainline: v5.8-rc2
Git-commit: 3003055f50663095472144994dac0339076031a8
References: bsc#1176447

After looking up for the flowtable hooks that need to be removed,
release the hook objects in the deletion list. The error path needs to
released these hook objects too.

Fixes: abadb2f865d7 ("netfilter: nf_tables: delete devices from flowtable")
Reported-by: syzbot+eb9d5924c51d6d59e094@syzkaller.appspotmail.com
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/netfilter/nf_tables_api.c |   31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6550,12 +6550,22 @@ err1:
 	return err;
 }
 
+static void nft_flowtable_hook_release(struct nft_flowtable_hook *flowtable_hook)
+{
+	struct nft_hook *this, *next;
+
+	list_for_each_entry_safe(this, next, &flowtable_hook->list, list) {
+		list_del(&this->list);
+		kfree(this);
+	}
+}
+
 static int nft_delflowtable_hook(struct nft_ctx *ctx,
 				 struct nft_flowtable *flowtable)
 {
 	const struct nlattr * const *nla = ctx->nla;
 	struct nft_flowtable_hook flowtable_hook;
-	struct nft_hook *this, *next, *hook;
+	struct nft_hook *this, *hook;
 	struct nft_trans *trans;
 	int err;
 
@@ -6564,33 +6574,40 @@ static int nft_delflowtable_hook(struct
 	if (err < 0)
 		return err;
 
-	list_for_each_entry_safe(this, next, &flowtable_hook.list, list) {
+	list_for_each_entry(this, &flowtable_hook.list, list) {
 		hook = nft_hook_list_find(&flowtable->hook_list, this);
 		if (!hook) {
 			err = -ENOENT;
 			goto err_flowtable_del_hook;
 		}
 		hook->inactive = true;
-		list_del(&this->list);
-		kfree(this);
 	}
 
 	trans = nft_trans_alloc(ctx, NFT_MSG_DELFLOWTABLE,
 				sizeof(struct nft_trans_flowtable));
-	if (!trans)
-		return -ENOMEM;
+	if (!trans) {
+		err = -ENOMEM;
+		goto err_flowtable_del_hook;
+	}
 
 	nft_trans_flowtable(trans) = flowtable;
 	nft_trans_flowtable_update(trans) = true;
 	INIT_LIST_HEAD(&nft_trans_flowtable_hooks(trans));
+	nft_flowtable_hook_release(&flowtable_hook);
 
 	list_add_tail(&trans->list, &ctx->net->nft.commit_list);
 
 	return 0;
 
 err_flowtable_del_hook:
-	list_for_each_entry(hook, &flowtable_hook.list, list)
+	list_for_each_entry(this, &flowtable_hook.list, list) {
+		hook = nft_hook_list_find(&flowtable->hook_list, this);
+		if (!hook)
+			break;
+
 		hook->inactive = false;
+	}
+	nft_flowtable_hook_release(&flowtable_hook);
 
 	return err;
 }