[PATCH 5.19 0145/1157] netfilter: nf_tables: fix null deref due to zeroed list head

Greg Kroah-Hartman
2022-08-15T22:30:31Z

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
@@ -153,6 +153,7 @@ 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;