#VU91494 Race condition in Linux kernel - CVE-2015-8839

Vulnerability identifier: #VU91494

Vulnerability risk: Medium

CVSSv4.0: 2.1 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2015-8839

CWE-ID: CWE-362

Exploitation vector: Local

Exploit availability: No

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

Vendor: Linux Foundation

Description

The vulnerability allows a local non-authenticated attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a race condition within the init_once() function in fs/ext4/super.c, within the ext4_punch_hole(), ext4_setattr(), ext4_page_mkwrite() and block_page_mkwrite_return() functions in fs/ext4/inode.c, within the ext4_dax_fault() and ext4_dax_pmd_fault() functions in fs/ext4/file.c, within the ext4_zero_range(), ext4_collapse_range() and ext4_insert_range() functions in fs/ext4/extents.c. A local non-authenticated attacker can perform a denial of service (DoS) attack.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: All versions

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External links
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ea3d7209ca01da209cda6f0dea8be9cc4b7a933b
https://www.openwall.com/lists/oss-security/2016/04/01/4
https://www.securityfocus.com/bid/85798
https://www.securitytracker.com/id/1035455
https://www.ubuntu.com/usn/USN-3005-1
https://www.ubuntu.com/usn/USN-3006-1
https://www.ubuntu.com/usn/USN-3007-1
https://access.redhat.com/errata/RHSA-2017:1842
https://access.redhat.com/errata/RHSA-2017:2077
https://access.redhat.com/errata/RHSA-2017:2669
https://bugzilla.redhat.com/show_bug.cgi?id=1323577
https://github.com/torvalds/linux/commit/ea3d7209ca01da209cda6f0dea8be9cc4b7a933b
https://lists.debian.org/debian-lts-announce/2020/06/msg00011.html
https://lists.debian.org/debian-lts-announce/2020/06/msg00013.html

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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.