The prctl_set_vma_anon_name function in kernel/sys.c in Android before 5.1.1 LMY49F and 6.0 before 2016-01-01 does not ensure that only one vma is accessed in a certain update action, which allows attackers to gain privileges or cause a denial of service (vma list corruption) via a crafted application, aka internal bug 20017123.