[PATCH 13/14] KVM: arm64: Enable the CONFIG_TEST UBSan for PKVM.

George-Aurelian Popescu
2020-09-14T17:30:56Z

From: George Popescu <georgepope@google.com>

Test the UBsan functionality for the hyp/nVHE code.
Because modules are not supported inside of hyp/nVHE code, the default
testing module for UBSan can not be used. For this purpose new functions
are defined inside of hyp/nVHE.

Test UBSan only when the hypervisor is initialized to prevent spamming
the boot messages.

Signed-off-by: George Popescu <georgepope@google.com>
---
arch/arm64/kvm/Kconfig | 3 +
arch/arm64/kvm/arm.c | 8 ++
arch/arm64/kvm/hyp/nvhe/Makefile | 1 +
arch/arm64/kvm/hyp/nvhe/ubsan_test.c | 115 +++++++++++++++++++++++++++
4 files changed, 127 insertions(+)
create mode 100644 arch/arm64/kvm/hyp/nvhe/ubsan_test.c

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 318c8f2df245..b6581f2512fb 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -60,6 +60,9 @@ config KVM_ARM_PMU
config KVM_INDIRECT_VECTORS
def_bool HARDEN_BRANCH_PREDICTOR || RANDOMIZE_BASE

+config NVHE_KVM_TEST_UBSAN
+ def_bool (TEST_UBSAN != n)
+
endif # KVM

endif # VIRTUALIZATION
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index eff57069e103..5468fa5599cf 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1297,6 +1297,14 @@ static void cpu_init_hyp_mode(void)
BUG_ON(!system_capabilities_finalized());
__kvm_call_hyp((void *)pgd_ptr, hyp_stack_ptr, vector_ptr, tpidr_el2);

+#ifdef CONFIG_NVHE_KVM_TEST_UBSAN
+ static bool test_ubsan_run;
+
+ if (!test_ubsan_run && (smp_processor_id() == 0)) {
+ test_ubsan_run = true;
+ kvm_call_hyp_nvhe(__kvm_test_ubsan);
+ }
+#endif
/*
* Disabling SSBD on a non-VHE system requires us to enable SSBS
* at EL2.
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index cc082e516353..2b495fe41f2b 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -12,6 +12,7 @@ obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \

CFLAGS_ubsan.hyp.tmp.o += -I $(srctree)/lib/
obj-$(CONFIG_UBSAN) += ubsan.o
+obj-$(CONFIG_NVHE_KVM_TEST_UBSAN) += ubsan_test.o

obj-y := $(patsubst %.o,%.hyp.o,$(obj-y))
extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y))
diff --git a/arch/arm64/kvm/hyp/nvhe/ubsan_test.c b/arch/arm64/kvm/hyp/nvhe/ubsan_test.c
new file mode 100644
index 000000000000..f4e7b3ed3cf5
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/ubsan_test.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/percpu-defs.h>
+#include <asm/kvm_asm.h>
+
+typedef void(*test_ubsan_fp)(void);
+
+static void test_ubsan_add_overflow(void)
+{
+ volatile int val = INT_MAX;
+
+ val += 2;
+}
+
+static void test_ubsan_sub_overflow(void)
+{
+ volatile int val = INT_MIN;
+ volatile int val2 = 2;
+
+ val -= val2;
+}
+
+static void test_ubsan_mul_overflow(void)
+{
+ volatile int val = INT_MAX / 2;
+
+ val *= 3;
+}
+
+static void test_ubsan_negate_overflow(void)
+{
+ volatile int val = INT_MIN;
+
+ val = -val;
+}
+
+static void test_ubsan_divrem_overflow(void)
+{
+ volatile int val = 16;
+ volatile int val2 = 0;
+
+ val /= val2;
+}
+
+static void test_ubsan_shift_out_of_bounds(void)
+{
+ volatile int val = -1;
+ int val2 = 10;
+
+ val2 <<= val;
+}
+
+static void test_ubsan_out_of_bounds(void)
+{
+ volatile int i = 4, j = 5;
+ volatile int arr[4];
+
+ arr[j] = i;
+}
+
+static void test_ubsan_load_invalid_value(void)
+{
+ volatile char *dst, *src;
+ bool val, val2, *ptr;
+ char c = 4;
+
+ dst = (char *)&val;
+ src = &c;
+ *dst = *src;
+
+ ptr = &val2;
+ val2 = val;
+}
+
+static void test_ubsan_misaligned_access(void)
+{
+ volatile char arr[5] __aligned(4) = {1, 2, 3, 4, 5};
+ volatile int *ptr, val = 6;
+
+ ptr = (int *)(arr + 1);
+ *ptr = val;
+}
+
+static void test_ubsan_object_size_mismatch(void)
+{
+ /* "((aligned(8)))" helps this not into be misaligned for ptr-access. */
+ volatile int val __aligned(8) = 4;
+ volatile long long *ptr, val2;
+
+ ptr = (long long *)&val;
+ val2 = *ptr;
+}
+
+static const test_ubsan_fp test_ubsan_array[] = {
+ test_ubsan_out_of_bounds,
+ test_ubsan_add_overflow,
+ test_ubsan_sub_overflow,
+ test_ubsan_mul_overflow,
+ test_ubsan_negate_overflow,
+ test_ubsan_divrem_overflow,
+ test_ubsan_shift_out_of_bounds,
+ test_ubsan_load_invalid_value,
+ test_ubsan_misaligned_access,
+ test_ubsan_object_size_mismatch,
+};
+
+void __kvm_test_ubsan(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(test_ubsan_array); i++)
+ test_ubsan_array[i]();
+}
--
2.28.0.618.gf4bc123cb7-goog