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authorPablo Neira Ayuso <pablo@netfilter.org>2019-03-08 00:58:53 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2019-03-08 16:41:18 +0100
commit40ba1d9b4d19796afc9b7ece872f5f3e8f5e2c13 (patch)
tree0135069f28adef774ecb6c8da6253caf180b85a5 /net
parentnetfilter: nat: don't register device notifier twice (diff)
downloadlinux-dev-40ba1d9b4d19796afc9b7ece872f5f3e8f5e2c13.tar.xz
linux-dev-40ba1d9b4d19796afc9b7ece872f5f3e8f5e2c13.zip
netfilter: nf_tables: fix set double-free in abort path
The abort path can cause a double-free of an anonymous set. Added-and-to-be-aborted rule looks like this: udp dport { 137, 138 } drop The to-be-aborted transaction list looks like this: newset newsetelem newsetelem rule This gets walked in reverse order, so first pass disables the rule, the set elements, then the set. After synchronize_rcu(), we then destroy those in same order: rule, set element, set element, newset. Problem is that the anonymous set has already been bound to the rule, so the rule (lookup expression destructor) already frees the set, when then cause use-after-free when trying to delete the elements from this set, then try to free the set again when handling the newset expression. Rule releases the bound set in first place from the abort path, this causes the use-after-free on set element removal when undoing the new element transactions. To handle this, skip new element transaction if set is bound from the abort path. This is still causes the use-after-free on set element removal. To handle this, remove transaction from the list when the set is already bound. Joint work with Florian Westphal. Fixes: f6ac85858976 ("netfilter: nf_tables: unbind set in rule from commit path") Bugzilla: https://bugzilla.netfilter.org/show_bug.cgi?id=1325 Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_tables_api.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index faf6bd10a19f..1333bf97dc26 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -142,7 +142,7 @@ static void nft_set_trans_bind(const struct nft_ctx *ctx, struct nft_set *set)
list_for_each_entry_reverse(trans, &net->nft.commit_list, list) {
if (trans->msg_type == NFT_MSG_NEWSET &&
nft_trans_set(trans) == set) {
- nft_trans_set_bound(trans) = true;
+ set->bound = true;
break;
}
}
@@ -6709,8 +6709,7 @@ static void nf_tables_abort_release(struct nft_trans *trans)
nf_tables_rule_destroy(&trans->ctx, nft_trans_rule(trans));
break;
case NFT_MSG_NEWSET:
- if (!nft_trans_set_bound(trans))
- nft_set_destroy(nft_trans_set(trans));
+ nft_set_destroy(nft_trans_set(trans));
break;
case NFT_MSG_NEWSETELEM:
nft_set_elem_destroy(nft_trans_elem_set(trans),
@@ -6783,8 +6782,11 @@ static int __nf_tables_abort(struct net *net)
break;
case NFT_MSG_NEWSET:
trans->ctx.table->use--;
- if (!nft_trans_set_bound(trans))
- list_del_rcu(&nft_trans_set(trans)->list);
+ if (nft_trans_set(trans)->bound) {
+ nft_trans_destroy(trans);
+ break;
+ }
+ list_del_rcu(&nft_trans_set(trans)->list);
break;
case NFT_MSG_DELSET:
trans->ctx.table->use++;
@@ -6792,8 +6794,11 @@ static int __nf_tables_abort(struct net *net)
nft_trans_destroy(trans);
break;
case NFT_MSG_NEWSETELEM:
+ if (nft_trans_elem_set(trans)->bound) {
+ nft_trans_destroy(trans);
+ break;
+ }
te = (struct nft_trans_elem *)trans->data;
-
te->set->ops->remove(net, te->set, &te->elem);
atomic_dec(&te->set->nelems);
break;