net: psp: do not inherit the Rx association on clone

sk->psp_assoc sits past sk_dontcopy_end, so sock_copy() copies it into
every socket accepted from a listener without taking a reference, while
inet_sock_destruct() puts for every inet socket. psp_twsk_init() does
refcount_inc() for the timewait socket, so a child closing through
TIME_WAIT cancels its own put and leaves the association with one
reference and N timewait sockets holding the same pointer. Closing the
listener frees it, and the timewait timers then put freed memory.

Rejecting the association on a listening socket is not sufficient: a socket
can acquire one while established and then be turned back into a listener,
because tcp_disconnect() leaves sk->psp_assoc in place.

  BUG: KASAN: slab-use-after-free in psp_twsk_assoc_free+0x6f/0xf0
  Write of size 4 at addr ffff888110f9255c by task swapper/7/0
   psp_twsk_assoc_free+0x6f/0xf0
   inet_twsk_put+0xda/0x1b0
   call_timer_fn+0x53/0x2e0
   __run_timers+0x764/0xa80
  Freed by task 99:
   kfree+0x1a7/0x500
   process_one_work+0x7ec/0x1100

An association carries a per-connection SPI and key, so a child must not
inherit the parent's. Clear it on clone.

Fixes: 6b46ca260e22 ("net: psp: add socket security association code")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: Norbert Szetei <norbert@doyensec.com>
Reviewed-by: Daniel Zahka <daniel.zahka@gmail.com>
Link: https://patch.msgid.link/BC10EB92-ABB3-41B2-AB16-266BEEBE18C0@doyensec.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions