[PATCH 08/14] KVM: arm64: Enable UBsan check for unreachable code inside hyp/nVHE code

George-Aurelian Popescu
2020-09-14T17:30:15Z

From: George Popescu <georgepope@google.com>

The data from __ubsan_handle_builtin_unreachable is passed to the buffer
and printed inside the kernel by its symmetric handler.

Signed-off-by: George Popescu <georgepope@google.com>
---
arch/arm64/include/asm/kvm_ubsan.h | 5 ++++-
arch/arm64/kvm/hyp/nvhe/ubsan.c | 12 +++++++++++-
arch/arm64/kvm/kvm_ubsan_buffer.c | 3 +++
3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_ubsan.h b/arch/arm64/include/asm/kvm_ubsan.h
index 575881e0bd5f..7fd0d0dfbd82 100644
--- a/arch/arm64/include/asm/kvm_ubsan.h
+++ b/arch/arm64/include/asm/kvm_ubsan.h
@@ -20,10 +20,12 @@ struct ubsan_values {
struct kvm_ubsan_info {
enum {
UBSAN_NONE,
- UBSAN_OUT_OF_BOUNDS
+ UBSAN_OUT_OF_BOUNDS,
+ UBSAN_UNREACHABLE_DATA
} type;
union {
struct out_of_bounds_data out_of_bounds_data;
+ struct unreachable_data unreachable_data;
};
union {
struct ubsan_values u_val;
@@ -32,3 +34,4 @@ struct kvm_ubsan_info {
#endif

void __ubsan_handle_out_of_bounds(void *_data, void *index);
+void __ubsan_handle_builtin_unreachable(void *_data);
diff --git a/arch/arm64/kvm/hyp/nvhe/ubsan.c b/arch/arm64/kvm/hyp/nvhe/ubsan.c
index b2d3404f6215..9497e7f7f397 100644
--- a/arch/arm64/kvm/hyp/nvhe/ubsan.c
+++ b/arch/arm64/kvm/hyp/nvhe/ubsan.c
@@ -58,6 +58,16 @@ void __ubsan_handle_out_of_bounds(void *_data, void *index)

void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) {}

-void __ubsan_handle_builtin_unreachable(void *_data) {}
+void __ubsan_handle_builtin_unreachable(void *_data)
+{
+ struct kvm_ubsan_info *slot;
+ struct unreachable_data *data = _data;
+
+ slot = kvm_ubsan_buffer_next_slot();
+ if (slot) {
+ slot->type = UBSAN_UNREACHABLE_DATA;
+ slot->unreachable_data = *data;
+ }
+}

void __ubsan_handle_load_invalid_value(void *_data, void *val) {}
diff --git a/arch/arm64/kvm/kvm_ubsan_buffer.c b/arch/arm64/kvm/kvm_ubsan_buffer.c
index ce796bdd027e..f66cc5f7878e 100644
--- a/arch/arm64/kvm/kvm_ubsan_buffer.c
+++ b/arch/arm64/kvm/kvm_ubsan_buffer.c
@@ -25,6 +25,9 @@ void __kvm_check_ubsan_data(struct kvm_ubsan_info *slot)
__ubsan_handle_out_of_bounds(&slot->out_of_bounds_data,
slot->u_val.lval);
break;
+ case UBSAN_UNREACHABLE_DATA:
+ __ubsan_handle_builtin_unreachable(&slot->unreachable_data);
+ break;
}
}

--
2.28.0.618.gf4bc123cb7-goog