UBUNTU-CVE-2026-98085: High severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: bpf: backtrackinsn(): Handle ld{abs,ind} subprog exit edge Nicholas Carlini reported a bug in precision backtracking mechanism for BPFLD | BPF{IND,ABS} instructions. These instructions are modelled as two branches: - fallthrough; - implicit exit from current subprogram. The implicit exit case was not handled by the backtrackinsn() function. When backtracking such a path backtrackinsn() did not call btsubprogenter(), which meant that backtracking continued manipulating precision marks in a caller frame, while looking at instructions in a callee frame. This lead to segmentation faults during verification (see the selftest), or unsound state pruning.