CVE-2021-3491 Information

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//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).

CVSS Vector

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

Reference

https://ubuntu.com/security/notices/USN-4949-1 https://ubuntu.com/security/notices/USN-4950-1 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1f82808877bb10d3deee7cf3374a4eb3fb582db https://www.zerodayinitiative.com/advisories/ZDI-21-589/ https://www.openwall.com/lists/oss-security/2021/05/11/13 https://security.netapp.com/advisory/ntap-20210716-0004/

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

8.8