1 files changed, 386 insertions, 0 deletions
diff --git a/lib/ubsan.c b/lib/ubsan.c
new file mode 100644
index 000000000..60c709985
--- /dev/null
+++ b/lib/ubsan.c
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * UBSAN error reporting functions
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/bug.h>
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <kunit/test-bug.h>
+
+#include "ubsan.h"
+
+static const char * const type_check_kinds[] = {
+	"load of",
+	"store to",
+	"reference binding to",
+	"member access within",
+	"member call on",
+	"constructor call on",
+	"downcast of",
+	"downcast of"
+};
+
+#define REPORTED_BIT 31
+
+#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
+#define COLUMN_MASK (~(1U << REPORTED_BIT))
+#define LINE_MASK   (~0U)
+#else
+#define COLUMN_MASK   (~0U)
+#define LINE_MASK (~(1U << REPORTED_BIT))
+#endif
+
+#define VALUE_LENGTH 40
+
+static bool was_reported(struct source_location *location)
+{
+	return test_and_set_bit(REPORTED_BIT, &location->reported);
+}
+
+static bool suppress_report(struct source_location *loc)
+{
+	return current->in_ubsan || was_reported(loc);
+}
+
+static bool type_is_int(struct type_descriptor *type)
+{
+	return type->type_kind == type_kind_int;
+}
+
+static bool type_is_signed(struct type_descriptor *type)
+{
+	WARN_ON(!type_is_int(type));
+	return  type->type_info & 1;
+}
+
+static unsigned type_bit_width(struct type_descriptor *type)
+{
+	return 1 << (type->type_info >> 1);
+}
+
+static bool is_inline_int(struct type_descriptor *type)
+{
+	unsigned inline_bits = sizeof(unsigned long)*8;
+	unsigned bits = type_bit_width(type);
+
+	WARN_ON(!type_is_int(type));
+
+	return bits <= inline_bits;
+}
+
+static s_max get_signed_val(struct type_descriptor *type, void *val)
+{
+	if (is_inline_int(type)) {
+		unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
+		unsigned long ulong_val = (unsigned long)val;
+
+		return ((s_max)ulong_val) << extra_bits >> extra_bits;
+	}
+
+	if (type_bit_width(type) == 64)
+		return *(s64 *)val;
+
+	return *(s_max *)val;
+}
+
+static bool val_is_negative(struct type_descriptor *type, void *val)
+{
+	return type_is_signed(type) && get_signed_val(type, val) < 0;
+}
+
+static u_max get_unsigned_val(struct type_descriptor *type, void *val)
+{
+	if (is_inline_int(type))
+		return (unsigned long)val;
+
+	if (type_bit_width(type) == 64)
+		return *(u64 *)val;
+
+	return *(u_max *)val;
+}
+
+static void val_to_string(char *str, size_t size, struct type_descriptor *type,
+			void *value)
+{
+	if (type_is_int(type)) {
+		if (type_bit_width(type) == 128) {
+#if defined(CONFIG_ARCH_SUPPORTS_INT128)
+			u_max val = get_unsigned_val(type, value);
+
+			scnprintf(str, size, "0x%08x%08x%08x%08x",
+				(u32)(val >> 96),
+				(u32)(val >> 64),
+				(u32)(val >> 32),
+				(u32)(val));
+#else
+			WARN_ON(1);
+#endif
+		} else if (type_is_signed(type)) {
+			scnprintf(str, size, "%lld",
+				(s64)get_signed_val(type, value));
+		} else {
+			scnprintf(str, size, "%llu",
+				(u64)get_unsigned_val(type, value));
+		}
+	}
+}
+
+static void ubsan_prologue(struct source_location *loc, const char *reason)
+{
+	current->in_ubsan++;
+
+	pr_err("========================================"
+		"========================================\n");
+	pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
+		loc->line & LINE_MASK, loc->column & COLUMN_MASK);
+
+	kunit_fail_current_test("%s in %s", reason, loc->file_name);
+}
+
+static void ubsan_epilogue(void)
+{
+	dump_stack();
+	pr_err("========================================"
+		"========================================\n");
+
+	current->in_ubsan--;
+
+	check_panic_on_warn("UBSAN");
+}
+
+void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
+{
+	struct overflow_data *data = _data;
+	char rhs_val_str[VALUE_LENGTH];
+
+	if (suppress_report(&data->location))
+		return;
+
+	ubsan_prologue(&data->location, "division-overflow");
+
+	val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
+
+	if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
+		pr_err("division of %s by -1 cannot be represented in type %s\n",
+			rhs_val_str, data->type->type_name);
+	else
+		pr_err("division by zero\n");
+
+	ubsan_epilogue();
+}
+EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
+
+static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
+{
+	if (suppress_report(data->location))
+		return;
+
+	ubsan_prologue(data->location, "null-ptr-deref");
+
+	pr_err("%s null pointer of type %s\n",
+		type_check_kinds[data->type_check_kind],
+		data->type->type_name);
+
+	ubsan_epilogue();
+}
+
+static void handle_misaligned_access(struct type_mismatch_data_common *data,
+				unsigned long ptr)
+{
+	if (suppress_report(data->location))
+		return;
+
+	ubsan_prologue(data->location, "misaligned-access");
+
+	pr_err("%s misaligned address %p for type %s\n",
+		type_check_kinds[data->type_check_kind],
+		(void *)ptr, data->type->type_name);
+	pr_err("which requires %ld byte alignment\n", data->alignment);
+
+	ubsan_epilogue();
+}
+
+static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
+					unsigned long ptr)
+{
+	if (suppress_report(data->location))
+		return;
+
+	ubsan_prologue(data->location, "object-size-mismatch");
+	pr_err("%s address %p with insufficient space\n",
+		type_check_kinds[data->type_check_kind],
+		(void *) ptr);
+	pr_err("for an object of type %s\n", data->type->type_name);
+	ubsan_epilogue();
+}
+
+static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
+				unsigned long ptr)
+{
+	unsigned long flags = user_access_save();
+
+	if (!ptr)
+		handle_null_ptr_deref(data);
+	else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
+		handle_misaligned_access(data, ptr);
+	else
+		handle_object_size_mismatch(data, ptr);
+
+	user_access_restore(flags);
+}
+
+void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
+				void *ptr)
+{
+	struct type_mismatch_data_common common_data = {
+		.location = &data->location,
+		.type = data->type,
+		.alignment = data->alignment,
+		.type_check_kind = data->type_check_kind
+	};
+
+	ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
+}
+EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
+
+void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
+{
+	struct type_mismatch_data_v1 *data = _data;
+	struct type_mismatch_data_common common_data = {
+		.location = &data->location,
+		.type = data->type,
+		.alignment = 1UL << data->log_alignment,
+		.type_check_kind = data->type_check_kind
+	};
+
+	ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
+}
+EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
+
+void __ubsan_handle_out_of_bounds(void *_data, void *index)
+{
+	struct out_of_bounds_data *data = _data;
+	char index_str[VALUE_LENGTH];
+
+	if (suppress_report(&data->location))
+		return;
+
+	ubsan_prologue(&data->location, "array-index-out-of-bounds");
+
+	val_to_string(index_str, sizeof(index_str), data->index_type, index);
+	pr_err("index %s is out of range for type %s\n", index_str,
+		data->array_type->type_name);
+	ubsan_epilogue();
+}
+EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
+
+void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
+{
+	struct shift_out_of_bounds_data *data = _data;
+	struct type_descriptor *rhs_type = data->rhs_type;
+	struct type_descriptor *lhs_type = data->lhs_type;
+	char rhs_str[VALUE_LENGTH];
+	char lhs_str[VALUE_LENGTH];
+	unsigned long ua_flags = user_access_save();
+
+	if (suppress_report(&data->location))
+		goto out;
+
+	ubsan_prologue(&data->location, "shift-out-of-bounds");
+
+	val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
+	val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
+
+	if (val_is_negative(rhs_type, rhs))
+		pr_err("shift exponent %s is negative\n", rhs_str);
+
+	else if (get_unsigned_val(rhs_type, rhs) >=
+		type_bit_width(lhs_type))
+		pr_err("shift exponent %s is too large for %u-bit type %s\n",
+			rhs_str,
+			type_bit_width(lhs_type),
+			lhs_type->type_name);
+	else if (val_is_negative(lhs_type, lhs))
+		pr_err("left shift of negative value %s\n",
+			lhs_str);
+	else
+		pr_err("left shift of %s by %s places cannot be"
+			" represented in type %s\n",
+			lhs_str, rhs_str,
+			lhs_type->type_name);
+
+	ubsan_epilogue();
+out:
+	user_access_restore(ua_flags);
+}
+EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
+
+
+void __ubsan_handle_builtin_unreachable(void *_data)
+{
+	struct unreachable_data *data = _data;
+	ubsan_prologue(&data->location, "unreachable");
+	pr_err("calling __builtin_unreachable()\n");
+	ubsan_epilogue();
+	panic("can't return from __builtin_unreachable()");
+}
+EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
+
+void __ubsan_handle_load_invalid_value(void *_data, void *val)
+{
+	struct invalid_value_data *data = _data;
+	char val_str[VALUE_LENGTH];
+
+	if (suppress_report(&data->location))
+		return;
+
+	ubsan_prologue(&data->location, "invalid-load");
+
+	val_to_string(val_str, sizeof(val_str), data->type, val);
+
+	pr_err("load of value %s is not a valid value for type %s\n",
+		val_str, data->type->type_name);
+
+	ubsan_epilogue();
+}
+EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
+
+void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
+					 unsigned long align,
+					 unsigned long offset);
+void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
+					 unsigned long align,
+					 unsigned long offset)
+{
+	struct alignment_assumption_data *data = _data;
+	unsigned long real_ptr;
+
+	if (suppress_report(&data->location))
+		return;
+
+	ubsan_prologue(&data->location, "alignment-assumption");
+
+	if (offset)
+		pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
+		       align, offset, data->type->type_name);
+	else
+		pr_err("assumption of %lu byte alignment for pointer of type %s failed",
+		       align, data->type->type_name);
+
+	real_ptr = ptr - offset;
+	pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
+	       offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
+	       real_ptr & (align - 1));
+
+	ubsan_epilogue();
+}
+EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);