doc: self-protection: Add information about STACKLEAK feature

Memory poisoning

Memory poisoning

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When releasing memory, it is best to poison the contents (clear stack on

When releasing memory, it is best to poison the contents, to avoid reuse

syscall return, wipe heap memory on a free), to avoid reuse attacks that

attacks that rely on the old contents of memory. E.g., clear stack on a

rely on the old contents of memory. This frustrates many uninitialized

syscall return (``CONFIG_GCC_PLUGIN_STACKLEAK``), wipe heap memory on a

variable attacks, stack content exposures, heap content exposures, and

free. This frustrates many uninitialized variable attacks, stack content

use-after-free attacks.

exposures, heap content exposures, and use-after-free attacks.

Destination tracking

Destination tracking

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