UBUNTU-CVE-2026-93174: Medium severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: bpf: Copy per-CPU map value padding in copymapvaluelong() In kernel, per-CPU map elements are stored with roundup(map->valuesize, 8) bytes. On UAPI lookup paths, it copies the rounded size for each CPU into a temporary buffer. However, copymapvaluelong() passes 'map->valuesize' to bpfobjmemcpy(). When the map has special fields, bpfobjmemcpy() copies around those fields with memcpy(), and does not copy the tail padding between 'map->valuesize' and roundup(map->valuesize, 8). The temporary UAPI lookup buffers are allocated without GFPZERO. As a result, when the per-CPU map's value size is not equal to roundup(map->valuesize, 8), UAPI LOOKUPELEM and its variants can return stale heap contents from that padding to user space. The same issue applies to bpfiter for per-CPU maps. Pass roundup(map->valuesize, 8) to bpfobjmemcpy() from copymapvaluelong(), so per-CPU maps both with and without special fields copy the entire per-CPU slot. Remove the now redundant roundup() from bpfobjmemcpy()'s longmemcpy path.