bpf: Reject negative offsets for ALU ops

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.

Timeline

1. Nov 12, 2025, 10:46 AM UTCCVE published
2. Oct 15, 2026, 9:57 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 15, 2026, 10:02 PM UTCRecord last updated

Affected versions

• Linux Linux

  From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 3bce44b344040e5eef3d64d38b157c15304c0aab; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 5017c302ca4b2a45149ad64e058fa2d5623c068f; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 21167bf70dbe400563e189ac632258d35eda38b5; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 55c0ced59fe17dee34e9dfd5f7be63cbab207758

• Linux Linux

  6.6

• KernelLinux

  From 6.6.0 · fixed in 6.6.112; From 6.7.0 · fixed in 6.12.53; From 6.13.0 · fixed in 6.17.3

References 4