CVS commit: src/sys

["Maxime Villard" <maxv%netbsd.org@localhost>]

Module Name:    src
Committed By:   maxv
Date:           Wed Aug 22 12:07:43 UTC 2018

Modified Files:
        src/sys/arch/amd64/amd64: asan.c machdep.c
        src/sys/arch/amd64/conf: Makefile.amd64
        src/sys/arch/amd64/include: param.h
        src/sys/arch/x86/x86: cpu_rng.c pmap.c
        src/sys/sys: cdefs.h
        src/sys/uvm: uvm_glue.c

Log Message:
Add support for monitoring the stack with kASan. This allows us to detect
illegal memory accesses occuring there.

The compiler inlines a piece of code in each function that adds redzones
around the local variables and poisons them. The illegal accesses are then
detected using the usual kASan machinery.

The stack size is doubled, from 4 pages to 8 pages.

Several boot functions are marked with the __noasan flag, to prevent the
compiler from adding redzones in them (because we haven't yet initialized
kASan). The kasan_early_init function is called early at boot time to
quickly create the shadow for the current stack; after this is done, we
don't need __noasan anymore in the boot path.

We pass -fasan-shadow-offset=0xDFFF900000000000, because the compiler
wants to do
        shad = shadow-offset + (addr >> 3)
and we do, in kasan_addr_to_shad
        shad = KASAN_SHADOW_START + ((addr - CANONICAL_BASE) >> 3)
hence
        shad = KASAN_SHADOW_START + (addr >> 3) - (CANONICAL_BASE >> 3)
             = [KASAN_SHADOW_START - (CANONICAL_BASE >> 3)] + (addr >> 3)
implies
        shadow-offset = KASAN_SHADOW_START - (CANONICAL_BASE >> 3)
                      = 0xFFFF800000000000 - (0xFFFF800000000000 >> 3)
                      = 0xDFFF900000000000

In UVM, we add a kasan_free (that is not preceded by a kasan_alloc). We
don't add poisoned redzones ourselves, but all the functions we execute
do, so we need to manually clear the poison before freeing the stack.

With the help of Kamil for the makefile stuff.


To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 src/sys/arch/amd64/amd64/asan.c
cvs rdiff -u -r1.315 -r1.316 src/sys/arch/amd64/amd64/machdep.c
cvs rdiff -u -r1.72 -r1.73 src/sys/arch/amd64/conf/Makefile.amd64
cvs rdiff -u -r1.25 -r1.26 src/sys/arch/amd64/include/param.h
cvs rdiff -u -r1.8 -r1.9 src/sys/arch/x86/x86/cpu_rng.c
cvs rdiff -u -r1.304 -r1.305 src/sys/arch/x86/x86/pmap.c
cvs rdiff -u -r1.136 -r1.137 src/sys/sys/cdefs.h
cvs rdiff -u -r1.163 -r1.164 src/sys/uvm/uvm_glue.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.