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 <lucien.xin@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
1 file changed