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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 14 Nov 2025 00:15:00 +0000
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threat_severity
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cvssV3_1
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Wed, 12 Nov 2025 23:00:00 +0000
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Linux
Linux linux Kernel |
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| Vendors & Products |
Linux
Linux linux Kernel |
Wed, 12 Nov 2025 11:00:00 +0000
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| Description | 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. | |
| Title | bpf: Reject negative offsets for ALU ops | |
| References |
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-11-12T10:46:51.736Z
Reserved: 2025-04-16T07:20:57.176Z
Link: CVE-2025-40169
No data.
Status : Awaiting Analysis
Published: 2025-11-12T11:15:47.270
Modified: 2025-11-12T16:19:12.850
Link: CVE-2025-40169
OpenCVE Enrichment
Updated: 2025-11-12T22:12:34Z