configs/common/generic: disable CONFIG_SLAB_MERGE_DEFAULT

Rafael Aquinirequested to merge
raquini/kernel-ark:disable-default-slab-merge into os-build

This is desired to reduce the risk of kernel heap overflows being able to overwrite objects from merged caches, and it changes the requirements for cache layout control, increasing the difficulty of these attacks.

It also in increases the reliability and protection against object data corruption due to use-after-free and double-free class of bugs, as by keeping caches unmerged, these kinds of issues can only damage objects in the same cache.

CONFIG_SLAB_MERGE_DEFAULT=n has been the default setting since RHEL-8

Signed-off-by: Rafael Aquini aquini@redhat.com

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