From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org,
pabeni@redhat.com, edumazet@google.com
Subject: [PATCH net 5/8] netfilter: ebtables: fix table blob use-after-free
Date: Wed, 22 Feb 2023 10:21:34 +0100 [thread overview]
Message-ID: <20230222092137.88637-6-pablo@netfilter.org> (raw)
In-Reply-To: <20230222092137.88637-1-pablo@netfilter.org>
From: Florian Westphal <fw@strlen.de>
We are not allowed to return an error at this point.
Looking at the code it looks like ret is always 0 at this
point, but its not.
t = find_table_lock(net, repl->name, &ret, &ebt_mutex);
... this can return a valid table, with ret != 0.
This bug causes update of table->private with the new
blob, but then frees the blob right away in the caller.
Syzbot report:
BUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168
Read of size 4 at addr ffffc90005425000 by task kworker/u4:4/74
Workqueue: netns cleanup_net
Call Trace:
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
__ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168
ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372
ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169
cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613
...
ip(6)tables appears to be ok (ret should be 0 at this point) but make
this more obvious.
Fixes: c58dd2dd443c ("netfilter: Can't fail and free after table replacement")
Reported-by: syzbot+f61594de72d6705aea03@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/bridge/netfilter/ebtables.c | 2 +-
net/ipv4/netfilter/ip_tables.c | 3 +--
net/ipv6/netfilter/ip6_tables.c | 3 +--
3 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index ce5dfa3babd2..757ec46fc45a 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1090,7 +1090,7 @@ static int do_replace_finish(struct net *net, struct ebt_replace *repl,
audit_log_nfcfg(repl->name, AF_BRIDGE, repl->nentries,
AUDIT_XT_OP_REPLACE, GFP_KERNEL);
- return ret;
+ return 0;
free_unlock:
mutex_unlock(&ebt_mutex);
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 2ed7c58b471a..aae5fd51dfd7 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1045,7 +1045,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
struct xt_counters *counters;
struct ipt_entry *iter;
- ret = 0;
counters = xt_counters_alloc(num_counters);
if (!counters) {
ret = -ENOMEM;
@@ -1091,7 +1090,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
net_warn_ratelimited("iptables: counters copy to user failed while replacing table\n");
}
vfree(counters);
- return ret;
+ return 0;
put_module:
module_put(t->me);
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 2d816277f2c5..ac902f7bca47 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1062,7 +1062,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
struct xt_counters *counters;
struct ip6t_entry *iter;
- ret = 0;
counters = xt_counters_alloc(num_counters);
if (!counters) {
ret = -ENOMEM;
@@ -1108,7 +1107,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
net_warn_ratelimited("ip6tables: counters copy to user failed while replacing table\n");
}
vfree(counters);
- return ret;
+ return 0;
put_module:
module_put(t->me);
--
2.30.2
next prev parent reply other threads:[~2023-02-22 9:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-22 9:21 [PATCH net 0/8] Netfilterf fixes for net Pablo Neira Ayuso
2023-02-22 9:21 ` [PATCH net 1/8] netfilter: nf_tables: allow to fetch set elements when table has an owner Pablo Neira Ayuso
2023-02-23 5:40 ` patchwork-bot+netdevbpf
2023-02-22 9:21 ` [PATCH net 2/8] netfilter: ctnetlink: fix possible refcount leak in ctnetlink_create_conntrack() Pablo Neira Ayuso
2023-02-22 9:21 ` [PATCH net 3/8] netfilter: conntrack: fix rmmod double-free race Pablo Neira Ayuso
2023-02-22 9:21 ` [PATCH net 4/8] netfilter: ip6t_rpfilter: Fix regression with VRF interfaces Pablo Neira Ayuso
2023-02-22 9:21 ` Pablo Neira Ayuso [this message]
2023-02-22 9:21 ` [PATCH net 6/8] netfilter: xt_length: use skb len to match in length_mt6 Pablo Neira Ayuso
2023-02-22 9:21 ` [PATCH net 7/8] netfilter: ctnetlink: make event listener tracking global Pablo Neira Ayuso
2023-02-22 9:21 ` [PATCH net 8/8] netfilter: x_tables: fix percpu counter block leak on error path when creating new netns Pablo Neira Ayuso
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