1 files changed, 315 insertions, 0 deletions
diff --git a/lib/kasan/generic.c b/lib/kasan/generic.c
new file mode 100644
index 0000000000..b33a6c1a6c
--- /dev/null
+++ b/lib/kasan/generic.c
@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file contains core generic KASAN code.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * Some code borrowed from https://github.com/xairy/kasan-prototype by
+ *        Andrey Konovalov <andreyknvl@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <common.h>
+
+#include "kasan.h"
+
+unsigned long kasan_shadow_start;
+unsigned long kasan_shadow_base;
+
+/*
+ * All functions below always inlined so compiler could
+ * perform better optimizations in each of __asan_loadX/__assn_storeX
+ * depending on memory access size X.
+ */
+
+static __always_inline bool memory_is_poisoned_1(unsigned long addr)
+{
+	s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(shadow_value)) {
+		s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
+		return unlikely(last_accessible_byte >= shadow_value);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
+						unsigned long size)
+{
+	u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
+
+	/*
+	 * Access crosses 8(shadow size)-byte boundary. Such access maps
+	 * into 2 shadow bytes, so we need to check them both.
+	 */
+	if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1))
+		return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
+
+	return memory_is_poisoned_1(addr + size - 1);
+}
+
+static __always_inline bool memory_is_poisoned_16(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	/* Unaligned 16-bytes access maps into 3 shadow bytes. */
+	if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
+		return *shadow_addr || memory_is_poisoned_1(addr + 15);
+
+	return *shadow_addr;
+}
+
+static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
+					size_t size)
+{
+	while (size) {
+		if (unlikely(*start))
+			return (unsigned long)start;
+		start++;
+		size--;
+	}
+
+	return 0;
+}
+
+static __always_inline unsigned long memory_is_nonzero(const void *start,
+						const void *end)
+{
+	unsigned int words;
+	unsigned long ret;
+	unsigned int prefix = (unsigned long)start % 8;
+
+	if (end - start <= 16)
+		return bytes_is_nonzero(start, end - start);
+
+	if (prefix) {
+		prefix = 8 - prefix;
+		ret = bytes_is_nonzero(start, prefix);
+		if (unlikely(ret))
+			return ret;
+		start += prefix;
+	}
+
+	words = (end - start) / 8;
+	while (words) {
+		if (unlikely(*(u64 *)start))
+			return bytes_is_nonzero(start, 8);
+		start += 8;
+		words--;
+	}
+
+	return bytes_is_nonzero(start, (end - start) % 8);
+}
+
+static __always_inline bool memory_is_poisoned_n(unsigned long addr,
+						size_t size)
+{
+	unsigned long ret;
+
+	ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
+			kasan_mem_to_shadow((void *)addr + size - 1) + 1);
+
+	if (unlikely(ret)) {
+		unsigned long last_byte = addr + size - 1;
+		s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
+
+		if (unlikely(ret != (unsigned long)last_shadow ||
+			((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
+			return true;
+	}
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
+{
+	if (__builtin_constant_p(size)) {
+		switch (size) {
+		case 1:
+			return memory_is_poisoned_1(addr);
+		case 2:
+		case 4:
+		case 8:
+			return memory_is_poisoned_2_4_8(addr, size);
+		case 16:
+			return memory_is_poisoned_16(addr);
+		default:
+			BUILD_BUG();
+		}
+	}
+
+	return memory_is_poisoned_n(addr, size);
+}
+
+static bool kasan_initialized;
+
+static __always_inline bool check_memory_region_inline(unsigned long addr,
+						size_t size, bool write,
+						unsigned long ret_ip)
+{
+	if (!kasan_initialized)
+		return true;
+
+	if (addr < kasan_shadow_start)
+		return true;
+
+	if (unlikely(size == 0))
+		return true;
+
+	if (unlikely(addr + size < addr))
+		return !kasan_report(addr, size, write, ret_ip);
+
+	if (addr < kasan_shadow_base)
+		return true;
+
+	if (likely(!memory_is_poisoned(addr, size)))
+		return true;
+
+	return !kasan_report(addr, size, write, ret_ip);
+}
+
+void kasan_init(unsigned long membase, unsigned long memsize,
+		unsigned long shadow_base)
+{
+	kasan_shadow_start = membase;
+	kasan_shadow_base = shadow_base;
+
+	kasan_unpoison_shadow((void *)membase, memsize);
+	kasan_initialized = true;
+}
+
+bool __no_sanitize_address check_memory_region(unsigned long addr,
+					       size_t size, bool write,
+					       unsigned long ret_ip)
+{
+	return check_memory_region_inline(addr, size, write, ret_ip);
+}
+
+static void register_global(struct kasan_global *global)
+{
+	size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
+
+	kasan_unpoison_shadow(global->beg, global->size);
+
+	kasan_poison_shadow(global->beg + aligned_size,
+		global->size_with_redzone - aligned_size,
+		KASAN_GLOBAL_REDZONE);
+}
+
+void __asan_register_globals(struct kasan_global *globals, size_t size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		register_global(&globals[i]);
+}
+EXPORT_SYMBOL(__asan_register_globals);
+
+void __asan_unregister_globals(struct kasan_global *globals, size_t size)
+{
+}
+EXPORT_SYMBOL(__asan_unregister_globals);
+
+#define DEFINE_ASAN_LOAD_STORE(size)					\
+	void __no_sanitize_address __asan_load##size(unsigned long addr)			\
+	{								\
+		check_memory_region_inline(addr, size, false, _RET_IP_);\
+	}								\
+	EXPORT_SYMBOL(__asan_load##size);				\
+	__alias(__asan_load##size)					\
+	void __no_sanitize_address __asan_load##size##_noabort(unsigned long);		\
+	EXPORT_SYMBOL(__asan_load##size##_noabort);			\
+	void __asan_store##size(unsigned long addr)			\
+	{								\
+		check_memory_region_inline(addr, size, true, _RET_IP_);	\
+	}								\
+	EXPORT_SYMBOL(__asan_store##size);				\
+	__alias(__asan_store##size)					\
+	void __asan_store##size##_noabort(unsigned long);		\
+	EXPORT_SYMBOL(__asan_store##size##_noabort)
+
+DEFINE_ASAN_LOAD_STORE(1);
+DEFINE_ASAN_LOAD_STORE(2);
+DEFINE_ASAN_LOAD_STORE(4);
+DEFINE_ASAN_LOAD_STORE(8);
+DEFINE_ASAN_LOAD_STORE(16);
+
+void __asan_loadN(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, false, _RET_IP_);
+}
+EXPORT_SYMBOL(__asan_loadN);
+
+__alias(__asan_loadN)
+void __asan_loadN_noabort(unsigned long, size_t);
+EXPORT_SYMBOL(__asan_loadN_noabort);
+
+void __asan_storeN(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, true, _RET_IP_);
+}
+EXPORT_SYMBOL(__asan_storeN);
+
+__alias(__asan_storeN)
+void __asan_storeN_noabort(unsigned long, size_t);
+EXPORT_SYMBOL(__asan_storeN_noabort);
+
+/* to shut up compiler complaints */
+void __asan_handle_no_return(void) {}
+EXPORT_SYMBOL(__asan_handle_no_return);
+
+/* Emitted by compiler to poison alloca()ed objects. */
+void __asan_alloca_poison(unsigned long addr, size_t size)
+{
+	size_t rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
+	size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
+			rounded_up_size;
+	size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_SIZE);
+
+	const void *left_redzone = (const void *)(addr -
+			KASAN_ALLOCA_REDZONE_SIZE);
+	const void *right_redzone = (const void *)(addr + rounded_up_size);
+
+	WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
+
+	kasan_unpoison_shadow((const void *)(addr + rounded_down_size),
+			      size - rounded_down_size);
+	kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
+			KASAN_ALLOCA_LEFT);
+	kasan_poison_shadow(right_redzone,
+			padding_size + KASAN_ALLOCA_REDZONE_SIZE,
+			KASAN_ALLOCA_RIGHT);
+}
+EXPORT_SYMBOL(__asan_alloca_poison);
+
+/* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
+void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
+{
+	if (unlikely(!stack_top || stack_top > stack_bottom))
+		return;
+
+	kasan_unpoison_shadow(stack_top, stack_bottom - stack_top);
+}
+EXPORT_SYMBOL(__asan_allocas_unpoison);
+
+/* Emitted by the compiler to [un]poison local variables. */
+#define DEFINE_ASAN_SET_SHADOW(byte) \
+	void __asan_set_shadow_##byte(const void *addr, size_t size)	\
+	{								\
+		__memset((void *)addr, 0x##byte, size);			\
+	}								\
+	EXPORT_SYMBOL(__asan_set_shadow_##byte)
+
+DEFINE_ASAN_SET_SHADOW(00);
+DEFINE_ASAN_SET_SHADOW(f1);
+DEFINE_ASAN_SET_SHADOW(f2);
+DEFINE_ASAN_SET_SHADOW(f3);
+DEFINE_ASAN_SET_SHADOW(f5);
+DEFINE_ASAN_SET_SHADOW(f8);