Debian 9 Critical: DLA-2940-1 Privilege Escalation and DoS Fixes

CVE-2021-3640

LinMa of BlockSec Team discovered a race condition in the
Bluetooth SCO implementation that can lead to a use-after-free. A
local user could exploit this to cause a denial of service (memory
corruption or crash) or possibly for privilege escalation.

CVE-2021-3752

Likang Luo of NSFOCUS Security Team discovered a flaw in the
Bluetooth L2CAP implementation that can lead to a user-after-free.
A local user could exploit this to cause a denial of service
(memory corruption or crash) or possibly for privilege escalation.

CVE-2021-4002

It was discovered that hugetlbfs, the virtual filesystem used by
applications to allocate huge pages in RAM, did not flush the
CPU's TLB in one case where it was necessary. In some
circumstances a local user would be able to read and write huge
pages after they are freed and reallocated to a different process.
This could lead to privilege escalation, denial of service or
information leaks.

CVE-2021-4083