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
