CVE-2021-3491 Linux kernel io_uring PROVIDE_BUFFERS MAX_RW_COUNT bypass

2021-05-1100:00:00

CWE-131

canonical

www.cve.org

7.8 High

CVSS3

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

8.8 High

AI Score

Confidence

High

0.001 Low

EPSS

Percentile

21.6%

JSON

The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem. This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was addressed via commit d1f82808877b (“io_uring: truncate lengths larger than MAX_RW_COUNT on provide buffers”) (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced in ddf0322db79c (“io_uring: add IORING_OP_PROVIDE_BUFFERS”) (v5.7-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"
      }
    ]
  }
]