The __get_user_asm_ex macro in arch/x86/include/asm/uaccess.h in the Linux kernel before 4.7.5 does not initialize a certain integer variable, which allows local users to obtain sensitive information from kernel stack memory by triggering failure of a get_user_ex call.

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.