#VU51549 Out-of-bounds write in Linux kernel - CVE-2020-29368

Vulnerability identifier: #VU51549

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-29368

CWE-ID: CWE-787

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a boundary error when processing untrusted input within the __split_huge_pmd() function in mm/huge_memory.c in the Linux kernel. A local user can abuse the copy-on-write implementation and gain unintended write access because of a race condition in a THP mapcount check.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.7.5, 5.7.5

---

External links
https://bugs.chromium.org/p/project-zero/issues/detail?id=2045
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.7.5
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c444eb564fb16645c172d550359cb3d75fe8a040
https://security.netapp.com/advisory/ntap-20210108-0002/

---

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.