[Xen-devel] [PATCH 0/3] gcc-plugins: Introduce stackinit plugin

[Kees Cook <keescook@xxxxxxxxxxxx>]

This adds a new plugin "stackinit" that attempts to perform unconditional
initialization of all stack variables[1]. It has wider effects than
GCC_PLUGIN_STRUCTLEAK_BYREF_ALL=y since BYREF_ALL does not consider
non-structures. A notable weakness is that padding bytes in many cases
remain uninitialized since GCC treats these bytes as "undefined". I'm
hoping we can improve the compiler (or the plugin) to cover that too.
(It's worth noting that BYREF_ALL actually does handle the padding --
I think this is due to the different method of detecting if initialization
is needed.)

Included is a tree-wide change to move switch variables up and out of
their switch and into the top-level variable declarations.

Included is a set of test cases for evaluating stack initialization,
which checks for padding, different types, etc.

Feedback welcome! :)

-Kees

[1] 
https://lkml.kernel.org/r/CA+55aFykZL+cSBJjBBts7ebEFfyGPdMzTmLSxKnT_29=j942dA@xxxxxxxxxxxxxx

Kees Cook (3):
  treewide: Lift switch variables out of switches
  gcc-plugins: Introduce stackinit plugin
  lib: Introduce test_stackinit module

 arch/x86/xen/enlighten_pv.c                   |   7 +-
 drivers/char/pcmcia/cm4000_cs.c               |   2 +-
 drivers/char/ppdev.c                          |  20 +-
 drivers/gpu/drm/drm_edid.c                    |   4 +-
 drivers/gpu/drm/i915/intel_display.c          |   2 +-
 drivers/gpu/drm/i915/intel_pm.c               |   4 +-
 drivers/net/ethernet/intel/e1000/e1000_main.c |   3 +-
 drivers/tty/n_tty.c                           |   3 +-
 drivers/usb/gadget/udc/net2280.c              |   5 +-
 fs/fcntl.c                                    |   3 +-
 lib/Kconfig.debug                             |   9 +
 lib/Makefile                                  |   1 +
 lib/test_stackinit.c                          | 327 ++++++++++++++++++
 mm/shmem.c                                    |   5 +-
 net/core/skbuff.c                             |   4 +-
 net/ipv6/ip6_gre.c                            |   4 +-
 net/ipv6/ip6_tunnel.c                         |   4 +-
 net/openvswitch/flow_netlink.c                |   7 +-
 scripts/Makefile.gcc-plugins                  |   6 +
 scripts/gcc-plugins/Kconfig                   |   9 +
 scripts/gcc-plugins/gcc-common.h              |  11 +-
 scripts/gcc-plugins/stackinit_plugin.c        |  79 +++++
 security/tomoyo/common.c                      |   3 +-
 security/tomoyo/condition.c                   |   7 +-
 security/tomoyo/util.c                        |   4 +-
 25 files changed, 484 insertions(+), 49 deletions(-)
 create mode 100644 lib/test_stackinit.c
 create mode 100644 scripts/gcc-plugins/stackinit_plugin.c

-- 
2.17.1


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