CVE-2025-40169

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxec0e2da95f72d4a46050a4d994e4fe471474fd80 < 3bce44b344040e5eef3d64d38b157c15304c0aabaffected
LinuxLinuxec0e2da95f72d4a46050a4d994e4fe471474fd80 < 5017c302ca4b2a45149ad64e058fa2d5623c068faffected
LinuxLinuxec0e2da95f72d4a46050a4d994e4fe471474fd80 < 21167bf70dbe400563e189ac632258d35eda38b5affected
LinuxLinuxec0e2da95f72d4a46050a4d994e4fe471474fd80 < 55c0ced59fe17dee34e9dfd5f7be63cbab207758affected
LinuxLinux6.6affected
LinuxLinux0 < 6.6unaffected
LinuxLinux6.6.112 <= 6.6.*unaffected
LinuxLinux6.12.53 <= 6.12.*unaffected
LinuxLinux6.17.3 <= 6.17.*unaffected
LinuxLinux6.18 <= *unaffected

Weaknesses

References