CVS commit: src/sys/kern

["Maxime Villard" <maxv%netbsd.org@localhost>]

Module Name:    src
Committed By:   maxv
Date:           Mon Mar 18 20:34:48 UTC 2019

Modified Files:
        src/sys/kern: subr_pool.c

Log Message:
Kernel Heap Hardening: manage freed items with bitmaps rather than linked
lists when we're on-page and the page header is naturally big enough to
contain a bitmap.

This comes with no increase in memory consumption, and similar CPU cost
(maybe it's a little faster actually).

We want to favor bitmaps over linked lists, because linked lists install
kernel pointers inside the items, and this can be too easily exploitable
in use-after-free or double-free conditions, or in item buffer overflows
occurring within a pool page.


To generate a diff of this commit:
cvs rdiff -u -r1.242 -r1.243 src/sys/kern/subr_pool.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.