From e8a1e58345cf40b7b272e08ac7b32328b2543e40 Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Wed, 28 Feb 2024 19:38:39 +0300 Subject: [PATCH] mac802154: fix llsec key resources release in mac802154_llsec_key_del mac802154_llsec_key_del() can free resources of a key directly without following the RCU rules for waiting before the end of a grace period. This may lead to use-after-free in case llsec_lookup_key() is traversing the list of keys in parallel with a key deletion: refcount_t: addition on 0; use-after-free. WARNING: CPU: 4 PID: 16000 at lib/refcount.c:25 refcount_warn_saturate+0x162/0x2a0 Modules linked in: CPU: 4 PID: 16000 Comm: wpan-ping Not tainted 6.7.0 #19 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x162/0x2a0 Call Trace: llsec_lookup_key.isra.0+0x890/0x9e0 mac802154_llsec_encrypt+0x30c/0x9c0 ieee802154_subif_start_xmit+0x24/0x1e0 dev_hard_start_xmit+0x13e/0x690 sch_direct_xmit+0x2ae/0xbc0 __dev_queue_xmit+0x11dd/0x3c20 dgram_sendmsg+0x90b/0xd60 __sys_sendto+0x466/0x4c0 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0x45/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Also, ieee802154_llsec_key_entry structures are not freed by mac802154_llsec_key_del(): unreferenced object 0xffff8880613b6980 (size 64): comm "iwpan", pid 2176, jiffies 4294761134 (age 60.475s) hex dump (first 32 bytes): 78 0d 8f 18 80 88 ff ff 22 01 00 00 00 00 ad de x......."....... 00 00 00 00 00 00 00 00 03 00 cd ab 00 00 00 00 ................ backtrace: [] __kmem_cache_alloc_node+0x1e2/0x2d0 [] kmalloc_trace+0x25/0xc0 [] mac802154_llsec_key_add+0xac9/0xcf0 [] ieee802154_add_llsec_key+0x5a/0x80 [] nl802154_add_llsec_key+0x426/0x5b0 [] genl_family_rcv_msg_doit+0x1fe/0x2f0 [] genl_rcv_msg+0x531/0x7d0 [] netlink_rcv_skb+0x169/0x440 [] genl_rcv+0x28/0x40 [] netlink_unicast+0x53c/0x820 [] netlink_sendmsg+0x93b/0xe60 [] ____sys_sendmsg+0xac5/0xca0 [] ___sys_sendmsg+0x11d/0x1c0 [] __sys_sendmsg+0xfa/0x1d0 [] do_syscall_64+0x45/0xf0 [] entry_SYSCALL_64_after_hwframe+0x6e/0x76 Handle the proper resource release in the RCU callback function mac802154_llsec_key_del_rcu(). Note that if llsec_lookup_key() finds a key, it gets a refcount via llsec_key_get() and locally copies key id from key_entry (which is a list element). So it's safe to call llsec_key_put() and free the list entry after the RCU grace period elapses. Found by Linux Verification Center (linuxtesting.org). Fixes: 5d637d5aabd8 ("mac802154: add llsec structures and mutators") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Acked-by: Alexander Aring Message-ID: <20240228163840.6667-1-pchelkin@ispras.ru> Signed-off-by: Stefan Schmidt --- include/net/cfg802154.h | 1 + net/mac802154/llsec.c | 18 +++++++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h index cd95711b12b8..76d2cd2e2b30 100644 --- a/include/net/cfg802154.h +++ b/include/net/cfg802154.h @@ -401,6 +401,7 @@ struct ieee802154_llsec_key { struct ieee802154_llsec_key_entry { struct list_head list; + struct rcu_head rcu; struct ieee802154_llsec_key_id id; struct ieee802154_llsec_key *key; diff --git a/net/mac802154/llsec.c b/net/mac802154/llsec.c index 8d2eabc71bbe..f13b07ebfb98 100644 --- a/net/mac802154/llsec.c +++ b/net/mac802154/llsec.c @@ -265,19 +265,27 @@ int mac802154_llsec_key_add(struct mac802154_llsec *sec, return -ENOMEM; } +static void mac802154_llsec_key_del_rcu(struct rcu_head *rcu) +{ + struct ieee802154_llsec_key_entry *pos; + struct mac802154_llsec_key *mkey; + + pos = container_of(rcu, struct ieee802154_llsec_key_entry, rcu); + mkey = container_of(pos->key, struct mac802154_llsec_key, key); + + llsec_key_put(mkey); + kfree_sensitive(pos); +} + int mac802154_llsec_key_del(struct mac802154_llsec *sec, const struct ieee802154_llsec_key_id *key) { struct ieee802154_llsec_key_entry *pos; list_for_each_entry(pos, &sec->table.keys, list) { - struct mac802154_llsec_key *mkey; - - mkey = container_of(pos->key, struct mac802154_llsec_key, key); - if (llsec_key_id_equal(&pos->id, key)) { list_del_rcu(&pos->list); - llsec_key_put(mkey); + call_rcu(&pos->rcu, mac802154_llsec_key_del_rcu); return 0; } }