linux-kernel - Re: [PATCH RFC v2 0/6] Break heap spraying needed for exploiting use-after-free

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Message-ID: <CA+DvKQ+-k9pk1mUrEiTRKzSsz1ugCiv1A3Owd97dop0HPXa6MA@mail.gmail.com>
Date:   Mon, 5 Oct 2020 22:19:10 -0400
From:   Daniel Micay <danielmicay@...il.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Matthew Wilcox <willy@...radead.org>, Jann Horn <jannh@...gle.com>,
        Alexander Popov <alex.popov@...ux.com>,
        Will Deacon <will@...nel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
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Subject: Re: [PATCH RFC v2 0/6] Break heap spraying needed for exploiting use-after-free

It will reuse the memory for other things when the whole slab is freed
though. Not really realistic to change that without it being backed by
virtual memory along with higher-level management of regions to avoid
intense fragmentation and metadata waste. It would depend a lot on
having much finer-grained slab caches, otherwise it's not going to be
much of an alternative to a quarantine feature. Even then, a
quarantine feature is still useful, but is less suitable for a
mainstream feature due to performance cost. Even a small quarantine
has a fairly high performance cost.