Medium [CVE-2026-52934] reject oversized TVLV packets

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tvlv: reject oversized TVLV packets batadv_tvlv_container_ogm_append() builds a TVLV packet section from the tvlv.container_list. The total size of this section is computed by batadv_tvlv_container_list_size(), which sums the sizes of all registered containers.

The return type and accumulator in batadv_tvlv_container_list_size() were u16. If the accumulated size exceeds U16_MAX, the value wraps around, causing the subsequent allocation in batadv_tvlv_container_ogm_append() to be undersized.

The memcpy-style copy that follows would then write beyond the end of the allocated buffer, corrupting kernel memory. Fix this by widening the return type of batadv_tvlv_container_list_size() to size_t.

In batadv_tvlv_container_ogm_append(), check the computed length against U16_MAX before proceeding, and bail out as if the allocation had failed when the limit is exceeded. A flaw was found in the Linux kernel's batman-adv (Better Approach To Mobile Ad-hoc Networking - Advanced) module.

An integer overflow vulnerability in the TVLV (Type-Length-Value) packet processing can lead to an undersized memory allocation. This allows a subsequent operation to write beyond the intended buffer, causing kernel memory corruption.