SB2016112805 - Permissions, Privileges, and Access Controls in Linux kernel

Description

This security bulletin contains information about 1 vulnerability.

1) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2016-9644)

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

CVSSv4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.

The __get_user_asm_ex macro in arch/x86/include/asm/uaccess.h in the Linux kernel 4.4.22 through 4.4.28 contains extended asm statements that are incompatible with the exception table, which allows local users to obtain root access on non-SMEP platforms via a crafted application. NOTE: this vulnerability exists because of incorrect backporting of the CVE-2016-9178 patch to older kernels.

Remediation

Install update from vendor's website.

References

• http://www.openwall.com/lists/oss-security/2016/11/07/4
• http://www.securityfocus.com/bid/94545
• http://www.ubuntu.com/usn/USN-3146-1
• http://www.ubuntu.com/usn/USN-3146-2
• https://lwn.net/Articles/705220/