Debian: DLA-2941-1 Critical: Linux 4.19 Privilege Escalation & DoS Fix

CVE-2020-29374

Jann Horn of Google reported a flaw in Linux's virtual memory
management. A parent and child process initially share all their
memory, but when either writes to a shared page, the page is
duplicated and unshared (copy-on-write). However, in case an
operation such as vmsplice() required the kernel to take an
additional reference to a shared page, and a copy-on-write occurs during this operation, the kernel might have accessed the wrong
process's memory. For some programs, this could lead to an
information leak or data corruption.

This issue was already fixed for most architectures, but not on
MIPS and System z. This update corrects that.

CVE-2020-36322, CVE-2021-28950

The syzbot tool found that the FUSE (filesystem-in-user-space)
implementation did not correctly handle a FUSE server returning
invalid attributes for a file. A local user permitted to run a
FUSE server could use this to cause a denial of service (crash).