The smbhash function in fs/cifs/smbencrypt.c in the Linux kernel 4.9.x before 4.9.1 interacts incorrectly with the CONFIG_VMAP_STACK option, which allows local users to cause a denial of service (system crash or memory corruption) or possibly have unspecified other impact by leveraging use of more than one virtual page for a scatterlist.
git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=06deeec77a5a689cc94b21a8a91a76e42176685d
www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.1
www.openwall.com/lists/oss-security/2017/01/21/3
www.securityfocus.com/bid/95714
bugzilla.redhat.com/show_bug.cgi?id=1416104
github.com/torvalds/linux/commit/06deeec77a5a689cc94b21a8a91a76e42176685d