| From 84e02a2ef96a70cd96ffb1c6953eb966a9d19411 Mon Sep 17 00:00:00 2001 |
| From: Florian Westphal <fw@strlen.de> |
| Date: Thu, 16 Jan 2020 12:03:01 +0100 |
| Subject: [PATCH] netfilter: nf_tables: fix flowtable list del corruption |
| |
| commit 335178d5429c4cee61b58f4ac80688f556630818 upstream. |
| |
| syzbot reported following crash: |
| |
| list_del corruption, ffff88808c9bb000->prev is LIST_POISON2 (dead000000000122) |
| [..] |
| Call Trace: |
| __list_del_entry include/linux/list.h:131 [inline] |
| list_del_rcu include/linux/rculist.h:148 [inline] |
| nf_tables_commit+0x1068/0x3b30 net/netfilter/nf_tables_api.c:7183 |
| [..] |
| |
| The commit transaction list has: |
| |
| NFT_MSG_NEWTABLE |
| NFT_MSG_NEWFLOWTABLE |
| NFT_MSG_DELFLOWTABLE |
| NFT_MSG_DELTABLE |
| |
| A missing generation check during DELTABLE processing causes it to queue |
| the DELFLOWTABLE operation a second time, so we corrupt the list here: |
| |
| case NFT_MSG_DELFLOWTABLE: |
| list_del_rcu(&nft_trans_flowtable(trans)->list); |
| nf_tables_flowtable_notify(&trans->ctx, |
| |
| because we have two different DELFLOWTABLE transactions for the same |
| flowtable. We then call list_del_rcu() twice for the same flowtable->list. |
| |
| The object handling seems to suffer from the same bug so add a generation |
| check too and only queue delete transactions for flowtables/objects that |
| are still active in the next generation. |
| |
| Reported-by: syzbot+37a6804945a3a13b1572@syzkaller.appspotmail.com |
| Fixes: 3b49e2e94e6eb ("netfilter: nf_tables: add flow table netlink frontend") |
| Signed-off-by: Florian Westphal <fw@strlen.de> |
| Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c |
| index c2ad8ce0d472..3c69d26e2f09 100644 |
| --- a/net/netfilter/nf_tables_api.c |
| +++ b/net/netfilter/nf_tables_api.c |
| @@ -979,12 +979,18 @@ static int nft_flush_table(struct nft_ctx *ctx) |
| } |
| |
| list_for_each_entry_safe(flowtable, nft, &ctx->table->flowtables, list) { |
| + if (!nft_is_active_next(ctx->net, flowtable)) |
| + continue; |
| + |
| err = nft_delflowtable(ctx, flowtable); |
| if (err < 0) |
| goto out; |
| } |
| |
| list_for_each_entry_safe(obj, ne, &ctx->table->objects, list) { |
| + if (!nft_is_active_next(ctx->net, obj)) |
| + continue; |
| + |
| err = nft_delobj(ctx, obj); |
| if (err < 0) |
| goto out; |
| -- |
| 2.7.4 |
| |