[RFC] UBSan: run-time undefined behavior sanity checker

[Andrey Ryabinin]

Hi

This is yet another sanitizer for linux kernel.

UBSan uses copile-time instumentation to catch undefined behavior (UB).
Compiler inserts code that perform certain kinds of
checks before operations that could cause UB.
If check fails (i.e. UB detected) __ubsan_handle_* function called.
to print error message.

Patch is also available via git:
	git://github.com/aryabinin/linux --branch ubsan/v1

GCC supports this since 4.9, however upcoming GCC 5.0 has
more checkers implemented.

Different kinds of checkers could be enabled via boot parameter:
ubsan_handle=OEAINVBSLF.
If ubsan_handle not present in cmdline default options are used: ELNVBSLF

	O - different kinds of overflows
	E - negation overflow, division overflow, division by zero.
	A - misaligned memory access.
	I - load from/store to an object with insufficient space.
	N - null argument declared with nonnull attribute,
		returned null from function which never returns null, null ptr dereference.
	V - variable size array with non-positive length
	B - out-of-bounds memory accesses.
	S - shifting out-of-bounds.
	L - load of invalid value (value out of range for the enum type, loading other then 0/1 to bool type)
	F - call to function through pointer with incorrect function type
		(AFAIK this is not implemented in gcc yet, probably works with clang,
		though I didn't check it).


Andrey Ryabinin (1):
  UBSan: run-time undefined behavior sanity checker

 Makefile                              |  12 +-
 arch/x86/Kconfig                      |   1 +
 arch/x86/boot/Makefile                |   1 +
 arch/x86/boot/compressed/Makefile     |   1 +
 arch/x86/realmode/rm/Makefile         |   1 +
 arch/x86/vdso/Makefile                |   2 +
 drivers/firmware/efi/libstub/Makefile |   1 +
 include/linux/sched.h                 |   4 +
 kernel/printk/Makefile                |   1 +
 lib/Kconfig.debug                     |  23 ++
 lib/Makefile                          |   3 +
 lib/ubsan.c                           | 559 ++++++++++++++++++++++++++++++++++
 lib/ubsan.h                           |  84 +++++
 scripts/Makefile.lib                  |   6 +
 14 files changed, 698 insertions(+), 1 deletion(-)
 create mode 100644 lib/ubsan.c
 create mode 100644 lib/ubsan.h

-- 
2.1.2

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