linux-kernel - Re: [PATCH wpan] mac802154: fix llsec key resources release in mac802154_llsec_key

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Date: Wed, 6 Mar 2024 22:19:34 +0100
From: Stefan Schmidt <stefan@...enfreihafen.org>
To: Fedor Pchelkin <pchelkin@...ras.ru>,
 Alexander Aring <alex.aring@...il.com>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Phoebe Buckheister <phoebe.buckheister@...m.fraunhofer.de>,
 linux-wpan@...r.kernel.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, Alexey Khoroshilov <khoroshilov@...ras.ru>,
 lvc-project@...uxtesting.org, stable@...r.kernel.org
Subject: Re: [PATCH wpan] mac802154: fix llsec key resources release in
 mac802154_llsec_key_del

Hello.

On 28.02.24 17:38, Fedor Pchelkin wrote:
> 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@...r.kernel.org
> Signed-off-by: Fedor Pchelkin <pchelkin@...ras.ru>

This patch has been applied to the wpan-next tree and will be
part of the next pull request to net-next. Thanks!

regards
Stefan Schmidt