Threats Tagged 'cve-2025-40169'

A vulnerability in the Linux kernel's BPF verifier allowed negative offsets in ALU operation instructions due to improper validation of the signed 16-bit offset field. This flaw permitted malformed BPF programs with offsets other than the explicitly allowed 0 or 1, potentially leading to high impact on confidentiality, integrity, and availability. The issue has been resolved by tightening the validation logic to reject any offset values other than 0 and 1.

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject negative offsets for ALU ops When verifying BPF programs, the check_alu_op() function validates instructions with ALU operations. The 'offset' field in these instructions is a signed 16-bit integer. The existing check 'insn->off > 1' was intended to ensure the offset is either 0, or 1 for BPF_MOD/BPF_DIV. However, because 'insn->off' is signed, this check incorrectly accepts all negative values (e.g., -1). This commit tightens the validation by changing the condition to '(insn->off != 0 && insn->off != 1)'. This ensures that any value other than the explicitly permitted 0 and 1 is rejected, hardening the verifier against malformed BPF programs.