PT-2016-5201 · Linux+3 · Linux Kernel+3

Dmitry Vyukov · Published 2016-01-13 · Updated 2016-12-03 · CVE-2016-2549

Positive Technologies (AI Summary)

CVSS v3.1

6.2

Medium

Base vector

AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 4.4.1

Description The issue allows local users to cause a denial of service (deadlock) via a crafted ioctl call due to the lack of prevention of recursive callback access in sound/core/hrtimer.c. This problem is not hypothetical and has been triggered by the syzkaller fuzzer. The previous fix is still insufficient, as it may cause a lockup when the ALSA timer instance reprograms itself in its callback, invoking the start function even in snd timer interrupt() that is called in hrtimer callback itself, resulting in a CPU stall.

Recommendations For Linux kernel versions prior to 4.4.1, update to version 4.4.1 or later to resolve the issue. As a temporary workaround, consider disabling the snd timer interrupt() function until a patch is available. Restrict access to the sound/core/hrtimer.c module to minimize the risk of exploitation. Avoid using the ioctl call in the affected API endpoint until the issue is resolved.

Fix

DoS

RCE

Weakness Enumeration

CWE-20

Related Identifiers

ALT-PU-2016-1018

ALT-PU-2016-1485

CVE-2016-2549

DSA-3503-1

OPENSUSE-SU-2016_2144-1

SUSE-SU-2016:0911-1

SUSE-SU-2016:1102-1

SUSE-SU-2016:1203-1

SUSE-SU-2016:2074-1

USN-2929-1

USN-2929-2

USN-2930-1

USN-2930-2

USN-2930-3

USN-2931-1

USN-2932-1

USN-2967-1

USN-2967-2

Affected Products

Alt Linux

Linux Kernel

Suse

Ubuntu

References · 250

• https://ubuntu.com/security/CVE-2015-8767 · Vendor Advisory
• https://ubuntu.com/security/CVE-2016-2546 · Vendor Advisory
• https://ubuntu.com/security/CVE-2016-2069 · Vendor Advisory
• https://osv.dev/vulnerability/DSA-3503-1 · Vendor Advisory
• https://osv.dev/vulnerability/USN-2929-1 · Vendor Advisory
• http://ubuntu.com/usn/USN-2930-1 · Vendor Advisory
• http://ubuntu.com/usn/USN-2967-2 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-2930-2 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2016:2074-1 · Vendor Advisory
• https://ubuntu.com/security/CVE-2016-2544 · Vendor Advisory
• http://ubuntu.com/usn/USN-2929-2 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-2967-1 · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2018-4134.html · Vendor Advisory
• https://ubuntu.com/security/CVE-2016-2384 · Vendor Advisory
• https://ubuntu.com/security/CVE-2016-2782 · Vendor Advisory