CVE-2021-3491

Description

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).

CvssV3 impact

BaseSeverity

HIGH

ConfidentialityImpact

HIGH

AttackComplexity

LOW

Scope

CHANGED

AttackVector

LOCAL

AvailabilityImpact

HIGH

IntegrityImpact

HIGH

PrivilegesRequired

LOW

BaseScore

8.8

VectorString

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

Version

3.1

UserInteraction

NONE

CvssV2 impact

AccessComplexity

LOW

ConfidentialityImpact

COMPLETE

AvailabilityImpact

COMPLETE

IntegrityImpact

COMPLETE

BaseScore

7.2

VectorString

AV:L/AC:L/Au:N/C:C/I:C/A:C

Version

2.0

AccessVector

LOCAL

Authentication

NONE