batman-adv: tt: limit local table to single TVLV response size

The reservation of local TT entries and VLANs only limits the local table
by (int) packet_size_max. But the full table response is sent as a single
unicast TVLV packet whose tvlv_len (covering the TVLV header and the TT
TVLV) is only 16 bit wide. The reservation must therefore be capped at the
minimum of both the packet_size_max and the maximum theoretic table
response.

The size limit was already missing the 16 bit tvlv_len cap since the
original packet_size_max check was introduced. But this check was only
reachable with fragmentation disabled and a hard interface MTU larger than
the maximum unicast TVLV packet. In this case,
batadv_tt_prepare_tvlv_local_data() refuses to build the full table
response and no oversized packet is created. It is therefore mostly
affecting the commit 85fb027f611b ("batman-adv: tt: reject VLAN/TT entries
before reaching size limit"), which should prevent this kind of
overallocation.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260930094558.3723766-2-sw%40simonwunderlich.de?part=8
Fixes: a19d3d85e1b8 ("batman-adv: limit local translation table max size")
Cc: <stable+noautosel@kernel.org> # requires 85fb027f611b, old behavior only affects MTU > 64KiB without fragmentation
Signed-off-by: Sven Eckelmann <sven@narfation.org>

0 files changed, 0 insertions, 0 deletions