According to CVE.MITRE, there are a several security issues on the linux kernel
4.4.x, there is the discription:
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.
The vulnerability affects:
Ubuntu Ubuntu Linux 16.04 LTS Ubuntu Ubuntu Linux 14.04 LTS Linux kernel 4.4.29 Linux kernel 4.4.28 Linux kernel 4.4.27 Linux kernel 4.4.25 Linux kernel 4.4.24
How to easily understand and patch the local privilege escalation on Ubuntu ?