CVE-2021-3444

Linux kernel bpf verifier incorrect mod32 truncation

Published Mar 23, 2021 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
Description
The bpf verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker with the ability to load bpf programs could use this gain out-of-bounds reads in kernel memory leading to information disclosure (kernel memory), and possibly out-of-bounds writes that could potentially lead to code execution. This issue was addressed in the upstream kernel in commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero") and in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101.

Remediation

Vendor Solution

Apply or update to a kernel that contains the commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero").

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-2785-1 linux-4.19 security update
EUVD EUVD EUVD-2021-26770 The bpf verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker with the ability to load bpf programs could use this gain out-of-bounds reads in kernel memory leading to information disclosure (kernel memory), and possibly out-of-bounds writes that could potentially lead to code execution. This issue was addressed in the upstream kernel in commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero") and in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101.
Ubuntu USN Ubuntu USN USN-4887-1 Linux kernel vulnerabilities
History

No history.

Weaknesses

Sources

Status
PUBLISHED
Assigner
canonical
Published
Updated
Sep 16, 2024, 5:27 PM
Reserved
Mar 16, 2021, 12:00 AM
Status
Modified
Published
Mar 23, 2021, 6:15 PM
Modified
Jun 17, 2026, 4:05 AM
Severity
Moderate
Public date
Feb 13, 2021, 12:00 AM