CVE-2026-31659

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

batman-adv: reject oversized global TT response buffers

batadvttpreparetvlvglobal_data() builds the allocation length for a global TT response in 16-bit temporaries. When a remote originator advertises a large enough global TT, the TT payload length plus the VLAN header offset can exceed 65535 and wrap before kmalloc().

The full-table response path still uses the original TT payload length when it fills ttchange, so the wrapped allocation is too small and batadvttpreparetvlvglobaldata() writes past the end of the heap object before the later packet-size check runs.

Fix this by rejecting TT responses whose TVLV value length cannot fit in the 16-bit TVLV payload length field.