Debian: DLA-993-2 Moderate: Java Application Fixes for Privilege Escalation

The Qualys Research Labs discovered that the size of the stack guard
page is not sufficiently large. The stack-pointer can jump over the
guard-page and moving from the stack into another memory region
without accessing the guard-page. In this case no page-fault
exception is raised and the stack extends into the other memory
region. An attacker can exploit this flaw for privilege escalation.

The default stack gap protection is set to 256 pages and can be
configured via the stack_guard_gap kernel parameter on the kernel
command line.

Further details can be found at
https://www.qualys.com/2017/06/19/stack-clash/stack-clash.txt

For Debian 7 "Wheezy", this problem has been fixed in version
3.2.89-2.

For Debian 8 "Jessie", this problem has been fixed in version
3.16.43-2+deb8u2.

For Debian 9 "Stretch", this problem has been fixed in version
4.9.30-2+deb9u2.

We recommend that you upgrade your linux packages.