[SRU][Focal-OEM-5.14/Jammy-OEM-5.17][PATCH 1/1] netfilter: nf_tables: fix null deref due to zeroed list head

[Yuxuan Luo]

From: Florian Westphal <fw at strlen.de>

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 at gmail.com>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
(cherry picked from commit 580077855a40741cf511766129702d97ff02f4d9)
CVE-2023-1095
Signed-off-by: Yuxuan Luo <yuxuan.luo at canonical.com>
---
 net/netfilter/nf_tables_api.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4faffdd81d2dd..c2ccccc69a601 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -116,6 +116,7 @@ static struct nft_trans *nft_trans_alloc(struct nft_ctx *ctx, int msg_type,
 	if (trans == NULL)
 		return NULL;
 
+	INIT_LIST_HEAD(&trans->list);
 	trans->msg_type = msg_type;
 	trans->ctx	= *ctx;
 
-- 
2.34.1