The ecryptfs_privileged_open function in fs/ecryptfs/kthread.c in the Linux kernel before 4.6.3 allows local users to gain privileges or cause a denial of service (stack memory consumption) via vectors involving crafted mmap calls for /proc pathnames, leading to recursive pagefault handling. It was found that stacking a file system over procfs in the Linux kernel could lead to a kernel stack overflow due to deep nesting, as demonstrated by mounting ecryptfs over procfs and creating a recursion by mapping /proc/environ. An unprivileged, local user could potentially use this flaw to escalate their privileges on the system.
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