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Date: Thu, 18 Apr 2019 17:42:05 +0200
From: Alexander Potapenko <glider@...gle.com>
To: akpm@...ux-foundation.org, cl@...ux.com, dvyukov@...gle.com,
keescook@...omium.org, labbott@...hat.com
Cc: linux-mm@...ck.org, linux-security-module@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 0/3] RFC: add init_allocations=1 boot option
Following the recent discussions here's another take at initializing
pages and heap objects with zeroes. This is needed to prevent possible
information leaks and make the control-flow bugs that depend on
uninitialized values more deterministic.
The patchset introduces a new boot option, init_allocations, which
makes page allocator and SL[AOU]B initialize newly allocated memory.
init_allocations=0 doesn't (hopefully) add any overhead to the
allocation fast path (no noticeable slowdown on hackbench).
With only the the first of the proposed patches the slowdown numbers are:
- 1.1% (stdev 0.2%) sys time slowdown building Linux kernel
- 3.1% (stdev 0.3%) sys time slowdown on af_inet_loopback benchmark
- 9.4% (stdev 0.5%) sys time slowdown on hackbench
The second patch introduces a GFP flag that allows to disable
initialization for certain allocations. The third page is an example of
applying it to af_unix.c, which helps hackbench greatly.
Slowdown numbers for the whole patchset are:
- 1.8% (stdev 0.8%) on kernel build
- 6.5% (stdev 0.2%) on af_inet_loopback
- 0.12% (stdev 0.6%) on hackbench
Alexander Potapenko (3):
mm: security: introduce the init_allocations=1 boot option
gfp: mm: introduce __GFP_NOINIT
net: apply __GFP_NOINIT to AF_UNIX sk_buff allocations
drivers/infiniband/core/uverbs_ioctl.c | 2 +-
include/linux/gfp.h | 6 ++++-
include/linux/mm.h | 8 +++++++
include/linux/slab_def.h | 1 +
include/linux/slub_def.h | 1 +
include/net/sock.h | 5 +++++
kernel/kexec_core.c | 4 ++--
mm/dmapool.c | 2 +-
mm/page_alloc.c | 18 ++++++++++++++-
mm/slab.c | 14 ++++++------
mm/slab.h | 1 +
mm/slab_common.c | 15 +++++++++++++
mm/slob.c | 3 ++-
mm/slub.c | 9 ++++----
net/core/sock.c | 31 +++++++++++++++++++++-----
net/unix/af_unix.c | 13 ++++++-----
16 files changed, 104 insertions(+), 29 deletions(-)
--
2.21.0.392.gf8f6787159e-goog
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