In the Linux kernel 5.5.0 and newer, the bpf verifier (kernel/bpf/verifier.c) did not properly restrict the register bounds for 32-bit operations, leading to out-of-bounds reads and writes in kernel memory. The vulnerability also affects the Linux 5.4 stable series, starting with v5.4.7, as the introducing commit was backported to that branch. This vulnerability was fixed in 5.6.1, 5.5.14, and 5.4.29. (issue is aka ZDI-CAN-10780)

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-4313-1 Linux kernel vulnerability
Fixes

Solution

Revert commit 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions").


Workaround

Mitigation for this vulnerability is available by setting the kernel.unprivileged_bpf_disabled sysctl to 1: $ sudo sysctl kernel.unprivileged_bpf_disabled=1 $ echo kernel.unprivileged_bpf_disabled=1 | sudo tee /etc/sysctl.d/90-CVE-2020-8835.conf This issue is also mitigated on systems that use secure boot with the kernel lockdown feature which blocks BPF program loading.

History

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Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: canonical

Published:

Updated: 2024-09-17T02:15:48.820Z

Reserved: 2020-02-10T00:00:00

Link: CVE-2020-8835

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2020-04-02T18:15:18.943

Modified: 2024-11-21T05:39:32.163

Link: CVE-2020-8835

cve-icon Redhat

Severity : Important

Publid Date: 2020-03-30T16:00:00Z

Links: CVE-2020-8835 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses