net/xfrm/xfrm_policy.c in the Linux kernel through 4.12.3, when CONFIG_XFRM_MIGRATE is enabled, does not ensure that the dir value of xfrm_userpolicy_id is XFRM_POLICY_MAX or less, which allows local users to cause a denial of service (out-of-bounds access) or possibly have unspecified other impact via an XFRM_MSG_MIGRATE xfrm Netlink message. Andrey Konovalov discovered that a divide-by-zero error existed in the TCP stack implementation in the Linux kernel. A local attacker could use this to cause a denial of service (system crash). Continue reading...
