The sg_ioctl function in drivers/scsi/sg.c in the Linux kernel before 4.13.4 allows local users to obtain sensitive information from uninitialized kernel heap-memory locations via an SG_GET_REQUEST_TABLE ioctl call for /dev/sg0.
https://usn.ubuntu.com/3754-1/
https://github.com/torvalds/linux/commit/3e0097499839e0fe3af380410eababe5a47c4cf9
http://www.securityfocus.com/bid/101187
http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.13.4