In the Linux kernel, the following vulnerability has been resolved:

wireguard: netlink: check for dangling peer via is_dead instead of empty list

If all peers are removed via wg_peer_remove_all(), rather than setting
peer_list to empty, the peer is added to a temporary list with a head on
the stack of wg_peer_remove_all(). If a netlink dump is resumed and the
cursored peer is one that has been removed via wg_peer_remove_all(), it
will iterate from that peer and then attempt to dump freed peers.

Fix this by instead checking peer->is_dead, which was explictly created
for this purpose. Also move up the device_update_lock lockdep assertion,
since reading is_dead relies on that.

It can be reproduced by a small script like:

    echo "Setting config..."
    ip link add dev wg0 type wireguard
    wg setconf wg0 /big-config
    (
            while true; do
                    echo "Showing config..."
                    wg showconf wg0 > /dev/null
            done
    ) &
    sleep 4
    wg setconf wg0 <(printf "[Peer]\nPublicKey=$(wg genkey)\n")

Resulting in:

    BUG: KASAN: slab-use-after-free in __lock_acquire+0x182a/0x1b20
    Read of size 8 at addr ffff88811956ec70 by task wg/59
    CPU: 2 PID: 59 Comm: wg Not tainted 6.8.0-rc2-debug+ #5
    Call Trace:
     <TASK>
     dump_stack_lvl+0x47/0x70
     print_address_description.constprop.0+0x2c/0x380
     print_report+0xab/0x250
     kasan_report+0xba/0xf0
     __lock_acquire+0x182a/0x1b20
     lock_acquire+0x191/0x4b0
     down_read+0x80/0x440
     get_peer+0x140/0xcb0
     wg_get_device_dump+0x471/0x1130

kernel.org https://git.kernel.org/stable/c/13d107794304306164481d31ce33f8fdb25a9c04 [No types assigned]

kernel.org https://git.kernel.org/stable/c/302b2dfc013baca3dea7ceda383930d9297d231d [No types assigned]

kernel.org https://git.kernel.org/stable/c/55b6c738673871c9b0edae05d0c97995c1ff08c4 [No types assigned]

kernel.org https://git.kernel.org/stable/c/710a177f347282eea162aec8712beb1f42d5ad87 [No types assigned]

kernel.org https://git.kernel.org/stable/c/7bedfe4cfa38771840a355970e4437cd52d4046b [No types assigned]

kernel.org https://git.kernel.org/stable/c/b7cea3a9af0853fdbb1b16633a458f991dde6aac [No types assigned]

kernel.org https://git.kernel.org/stable/c/f52be46e3e6ecefc2539119784324f0cbc09620a [No types assigned]