From a907e36d54e0ff836e55e04531be201bf6b4d8c8 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 7 Dec 2015 18:48:07 +0800 Subject: [PATCH] netfilter: nf_tables: use reverse traversal commit_list in nf_tables_abort When we use 'nft -f' to submit rules, it will build multiple rules into one netlink skb to send to kernel, kernel will process them one by one. meanwhile, it add the trans into commit_list to record every commit. if one of them's return value is -EAGAIN, status |= NFNL_BATCH_REPLAY will be marked. after all the process is done. it will roll back all the commits. now kernel use list_add_tail to add trans to commit, and use list_for_each_entry_safe to roll back. which means the order of adding and rollback is the same. that will cause some cases cannot work well, even trigger call trace, like: 1. add a set into table foo [return -EAGAIN]: commit_list = 'add set trans' 2. del foo: commit_list = 'add set trans' -> 'del set trans' -> 'del tab trans' then nf_tables_abort will be called to roll back: firstly process 'add set trans': case NFT_MSG_NEWSET: trans->ctx.table->use--; list_del_rcu(&nft_trans_set(trans)->list); it will del the set from the table foo, but it has removed when del table foo [step 2], then the kernel will panic. the right order of rollback should be: 'del tab trans' -> 'del set trans' -> 'add set trans'. which is opposite with commit_list order. so fix it by rolling back commits with reverse order in nf_tables_abort. Signed-off-by: Xin Long Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index f1002dcfa1c9..2cb429d34c03 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -4024,7 +4024,8 @@ static int nf_tables_abort(struct sk_buff *skb) struct nft_trans *trans, *next; struct nft_trans_elem *te; - list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) { + list_for_each_entry_safe_reverse(trans, next, &net->nft.commit_list, + list) { switch (trans->msg_type) { case NFT_MSG_NEWTABLE: if (nft_trans_table_update(trans)) { -- 2.30.2