#VU12339 Race condition in Linux kernel - CVE-2015-9016

Vulnerability identifier: #VU12339

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-2015-9016

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

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

Vendor: Linux Foundation

Description
The vulnerability allows a local attacker to gain elevated privileges on the target system.

The weakness exists in blk_mq_tag_to_rq in blk-mq.c due to race condition when a request has been previously freed by blk_mq_complete_request. A local attacker can trigger use-after-free error and gain root privileges.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: 3.19 - 3.19.8, 4.0 - 4.0.1

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External links
https://github.com/torvalds/linux/commit/0048b4837affd153897ed1222283492070027aa9

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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.