CVE-2021-3490 Linux kernel eBPF bitwise ops ALU32 bounds tracking

2021-06-0401:40:20

CWE-787

CWE-20

canonical

www.cve.org

ebpf

alu32

bounds tracking

linux kernel

bitwise ops

out of bounds reads

arbitrary code execution

commit

fix

stable kernels

CVSS3

7.8

Attack Vector

LOCAL

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

AI Score

8.4

Confidence

High

EPSS

0.002

Percentile

57.3%

JSON

The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e (“bpf: Fix alu32 const subreg bound tracking on bitwise operations”) (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 (“bpf: Verifier, do explicit ALU32 bounds tracking”) (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 (“bpf:Fix a verifier failure with xor”) ( 5.10-rc1).

CNA Affected

[
  {
    "product": "Linux kernel",
    "vendor": "Linux",
    "versions": [
      {
        "lessThan": "v5.13-rc4",
        "status": "affected",
        "version": "trunk",
        "versionType": "custom"
      },
      {
        "lessThan": "v5.12.4",
        "status": "affected",
        "version": "linux-5.12.y",
        "versionType": "custom"
      },
      {
        "lessThan": "v5.11.21",
        "status": "affected",
        "version": "linux-5.11.y",
        "versionType": "custom"
      },
      {
        "lessThan": "v5.10.37",
        "status": "affected",
        "version": "linux-5.10.y",
        "versionType": "custom"
      },
      {
        "lessThan": "5.7*",
        "status": "affected",
        "version": "v5.7-rc1",
        "versionType": "custom"
      }
    ]
  }
]