[PATCH net v4 0/2] amt: send the relay's General Query directly from the receive path

[Omar Ramadan <omar@blockcast.net>]

The relay queues its General Query on the amt device with a raw tunnel
pointer in skb->cb, and a query that waits in a qdisc can outlive its
tunnel: a use-after-free in amt_dev_xmit(), reported by Microsoft with
a KASAN reproducer. Patch 1 sends the query directly from
amt_request_handler(), inside the RCU section that found or created
the tunnel, so it never waits in a qdisc and nothing is stored in
skb->cb.

Patch 2 adds the selftest Taehee asked for. It counts the queries that
leave the relay through its amt device and expects none. It fails
without patch 1 and passes with it.

v4: patch 1 is unchanged from v3; patch 2 is new.
v3: https://lore.kernel.org/netdev/20260928181601.85857-1-omar@blockcast.net/
v2: https://lore.kernel.org/netdev/20260922214150.13970-1-cenzhang@linux.microsoft.com/

Omar Ramadan (2):
  amt: send the relay's General Query directly from the receive path
  selftests: net: amt: check that the relay's queries bypass the amt
    device

 drivers/net/amt.c                  | 48 ++++++++++--------------------
 include/net/amt.h                  |  4 ---
 tools/testing/selftests/net/amt.sh | 29 ++++++++++++++++++
 3 files changed, 44 insertions(+), 37 deletions(-)


base-commit: a7bfaba4823e3c165bb2004c74eff7c096672bc7
-- 
2.47.3