The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Thanks, Sasha

------------------ original commit in Linus's tree ------------------

From e8a1e58345cf40b7b272e08ac7b32328b2543e40 Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin pchelkin@ispras.ru 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: <TASK> 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: [<ffffffff81dcfa62>] __kmem_cache_alloc_node+0x1e2/0x2d0 [<ffffffff81c43865>] kmalloc_trace+0x25/0xc0 [<ffffffff88968b09>] mac802154_llsec_key_add+0xac9/0xcf0 [<ffffffff8896e41a>] ieee802154_add_llsec_key+0x5a/0x80 [<ffffffff8892adc6>] nl802154_add_llsec_key+0x426/0x5b0 [<ffffffff86ff293e>] genl_family_rcv_msg_doit+0x1fe/0x2f0 [<ffffffff86ff46d1>] genl_rcv_msg+0x531/0x7d0 [<ffffffff86fee7a9>] netlink_rcv_skb+0x169/0x440 [<ffffffff86ff1d88>] genl_rcv+0x28/0x40 [<ffffffff86fec15c>] netlink_unicast+0x53c/0x820 [<ffffffff86fecd8b>] netlink_sendmsg+0x93b/0xe60 [<ffffffff86b91b35>] ____sys_sendmsg+0xac5/0xca0 [<ffffffff86b9c3dd>] ___sys_sendmsg+0x11d/0x1c0 [<ffffffff86b9c65a>] __sys_sendmsg+0xfa/0x1d0 [<ffffffff88eadbf5>] do_syscall_64+0x45/0xf0 [<ffffffff890000ea>] 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 pchelkin@ispras.ru Acked-by: Alexander Aring aahringo@redhat.com Message-ID: 20240228163840.6667-1-pchelkin@ispras.ru Signed-off-by: Stefan Schmidt stefan@datenfreihafen.org --- 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 cd95711b12b8e..76d2cd2e2b309 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 8d2eabc71bbeb..f13b07ebfb98a 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; } }