[src/trunk]: src/sys Add support for use-after-scope detection in KASAN. It i...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/eb8954e08fe0
branches:  trunk
changeset: 839523:eb8954e08fe0
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Feb 24 08:02:45 2019 +0000

description:
Add support for use-after-scope detection in KASAN. It is available since
GCC7, and we have GCC7 by default now.

Slightly reorder the code, and remove a duplicated KASSERT too.

Tested on amd64-KASAN. Not yet enabled on aarch64-KASAN, but it should
work as-is.

diffstat:

 sys/arch/amd64/conf/Makefile.amd64 |   3 ++-
 sys/kern/subr_asan.c               |  36 +++++++++++++++++++++++++++---------
 2 files changed, 29 insertions(+), 10 deletions(-)

diffs (88 lines):

diff -r 3779d4b5c274 -r eb8954e08fe0 sys/arch/amd64/conf/Makefile.amd64
--- a/sys/arch/amd64/conf/Makefile.amd64        Sun Feb 24 07:39:33 2019 +0000
+++ b/sys/arch/amd64/conf/Makefile.amd64        Sun Feb 24 08:02:45 2019 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: Makefile.amd64,v 1.75 2018/10/31 06:26:25 maxv Exp $
+#      $NetBSD: Makefile.amd64,v 1.76 2019/02/24 08:02:45 maxv Exp $
 
 # Makefile for NetBSD
 #
@@ -52,6 +52,7 @@
 .if ${KASAN:U0} > 0 && ${HAVE_GCC:U0} > 0
 KASANFLAGS=    -fsanitize=kernel-address \
                --param asan-globals=1 --param asan-stack=1 \
+               -fsanitize-address-use-after-scope \
                -fasan-shadow-offset=0xDFFF900000000000
 .for f in subr_asan.c
 KASANFLAGS.${f}=       # empty
diff -r 3779d4b5c274 -r eb8954e08fe0 sys/kern/subr_asan.c
--- a/sys/kern/subr_asan.c      Sun Feb 24 07:39:33 2019 +0000
+++ b/sys/kern/subr_asan.c      Sun Feb 24 08:02:45 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_asan.c,v 1.3 2019/02/13 14:55:29 kamil Exp $      */
+/*     $NetBSD: subr_asan.c,v 1.4 2019/02/24 08:02:45 maxv Exp $       */
 
 /*
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_asan.c,v 1.3 2019/02/13 14:55:29 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_asan.c,v 1.4 2019/02/24 08:02:45 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/device.h>
@@ -182,6 +182,16 @@
 }
 
 static __always_inline void
+kasan_shadow_Nbyte_markvalid(const void *addr, size_t size)
+{
+       size_t i;
+
+       for (i = 0; i < size; i++) {
+               kasan_shadow_1byte_markvalid((unsigned long)addr+i);
+       }
+}
+
+static __always_inline void
 kasan_shadow_Nbyte_fill(const void *addr, size_t size, uint8_t val)
 {
        void *shad;
@@ -210,16 +220,10 @@
 static void
 kasan_markmem(const void *addr, size_t size, bool valid)
 {
-       size_t i;
-
        KASSERT((vaddr_t)addr % KASAN_SHADOW_SCALE_SIZE == 0);
-
        if (valid) {
-               for (i = 0; i < size; i++) {
-                       kasan_shadow_1byte_markvalid((unsigned long)addr+i);
-               }
+               kasan_shadow_Nbyte_markvalid(addr, size);
        } else {
-               KASSERT(size % KASAN_SHADOW_SCALE_SIZE == 0);
                kasan_shadow_Nbyte_fill(addr, size, KASAN_MEMORY_REDZONE);
        }
 }
@@ -537,3 +541,17 @@
 ASAN_SET_SHADOW(f3);
 ASAN_SET_SHADOW(f5);
 ASAN_SET_SHADOW(f8);
+
+void __asan_poison_stack_memory(const void *, size_t);
+void __asan_unpoison_stack_memory(const void *, size_t);
+
+void __asan_poison_stack_memory(const void *addr, size_t size)
+{
+       size = roundup(size, KASAN_SHADOW_SCALE_SIZE);
+       kasan_shadow_Nbyte_fill(addr, size, KASAN_USE_AFTER_SCOPE);
+}
+
+void __asan_unpoison_stack_memory(const void *addr, size_t size)
+{
+       kasan_shadow_Nbyte_markvalid(addr, size);
+}