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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, mingi cho <mgcho.minic@gmail.com>,
        Florian Westphal <fw@strlen.de>,
        Pablo Neira Ayuso <pablo@netfilter.org>
Subject: [PATCH 4.19 038/287] netfilter: nf_tables: fix null deref due to zeroed list head
Date:   Tue, 23 Aug 2022 10:23:27 +0200
Message-Id: <20220823080101.550008403@linuxfoundation.org>
In-Reply-To: <20220823080100.268827165@linuxfoundation.org>
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From: Florian Westphal <fw@strlen.de>

commit 580077855a40741cf511766129702d97ff02f4d9 upstream.

In nf_tables_updtable, if nf_tables_table_enable returns an error,
nft_trans_destroy is called to free the transaction object.

nft_trans_destroy() calls list_del(), but the transaction was never
placed on a list -- the list head is all zeroes, this results in
a null dereference:

BUG: KASAN: null-ptr-deref in nft_trans_destroy+0x26/0x59
Call Trace:
 nft_trans_destroy+0x26/0x59
 nf_tables_newtable+0x4bc/0x9bc
 [..]

Its sane to assume that nft_trans_destroy() can be called
on the transaction object returned by nft_trans_alloc(), so
make sure the list head is initialised.

Fixes: 55dd6f93076b ("netfilter: nf_tables: use new transaction infrastructure to handle table")
Reported-by: mingi cho <mgcho.minic@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/netfilter/nf_tables_api.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -96,6 +96,7 @@ static struct nft_trans *nft_trans_alloc
 	if (trans == NULL)
 		return NULL;
 
+	INIT_LIST_HEAD(&trans->list);
 	trans->msg_type = msg_type;
 	trans->ctx	= *ctx;