UBUNTU-CVE-2026-93045: High severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject arena frees below the arena base bpfarenafreepages() accepts scalar arena addresses. The runtime masks the address to the low 32 bits and reconstructs a full user address from the arena base before returning the range to the arena free tree. When the scalar value is below the low 32 bits of the arena base, fulluaddr falls below uservmstart. The existing upper-end clipping then turns this into an out-of-range free-tree offset. A later allocation can reuse that offset and return an address below the arena mapping. Reject such frees before computing the clipped range.