SB2017120713 - Ubuntu update for Linux kernel (HWE)

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Use-after-free error (CVE-ID: CVE-2017-16939)

The vulnerability allows a local attacker to cause DoS condition on the target system.

The weakness exists in the XFRM dump policy implementation in net/xfrm/xfrm_user.c in the Linux kernel due to use-after-free error. A local attacker can make a specially crafted SO_RCVBUF setsockopt system call in conjunction with XFRM_MSG_GETPOLICY Netlink messages, trigger memory corruption and cause the service to crash.

Successful exploitation of the vulnerability results in denial of service.

2) Race condition (CVE-ID: CVE-2017-1000405)

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to a race condition within touch_pmd() function in mmhugemem.c file when handling THPs. A local user can read read-only huge pages using the get_user_pages() function and overwrite arbitrary huge pages and files mapped via THP.

Successful exploitation of the vulnerability may allow an attacker to perform a denial of service (DoS) attack.

This vulnerability is a result of patch against a another privilege escalation vulnerability in Linux kernel known as Dirty Cow (CVE-2016-5195).

3) Race condition (CVE-ID: CVE-2017-12146)

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

The vulnerability exists due to a race condition between a read operation and a store operation that involve different overrides in driver_override implementation in drivers/base/platform.c. A local user can execute arbitrary code on the target system with elevated privileges.

Remediation

Install update from vendor's website.

References

• http://www.ubuntu.com/usn/usn-3508-2/