CVE-2026-98085

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

bpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge

Nicholas Carlini reported a bug in precision backtracking mechanism

for BPF_LD | 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 backtrack_insn()

function. When backtracking such a path backtrack_insn() did not

call bt_subprog_enter(), 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.