kasan: split out generic_report.c from report.c

Move generic KASAN specific error reporting routines to generic_report.c
without any functional changes, leaving common error reporting code in
report.c to be later reused by tag-based KASAN.

Link: http://lkml.kernel.org/r/ba48c32f8e5aefedee78998ccff0413bee9e0f5b.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/kasan/Makefile

@@ -14,5 +14,5 @@ CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 
 obj-$(CONFIG_KASAN) := common.o init.o report.o
-obj-$(CONFIG_KASAN_GENERIC) += generic.o quarantine.o
-obj-$(CONFIG_KASAN_SW_TAGS) += tags.o
+obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o
+obj-$(CONFIG_KASAN_SW_TAGS) += tags.o tags_report.o

mm/kasan/generic_report.c

@@ -0,0 +1,158 @@
+/*
+ * This file contains generic KASAN specific error reporting 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.
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/ftrace.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/stackdepot.h>
+#include <linux/stacktrace.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/kasan.h>
+#include <linux/module.h>
+
+#include <asm/sections.h>
+
+#include "kasan.h"
+#include "../slab.h"
+
+static const void *find_first_bad_addr(const void *addr, size_t size)
+{
+	u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
+	const void *first_bad_addr = addr;
+
+	while (!shadow_val && first_bad_addr < addr + size) {
+		first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
+		shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
+	}
+	return first_bad_addr;
+}
+
+static const char *get_shadow_bug_type(struct kasan_access_info *info)
+{
+	const char *bug_type = "unknown-crash";
+	u8 *shadow_addr;
+
+	info->first_bad_addr = find_first_bad_addr(info->access_addr,
+						info->access_size);
+
+	shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
+
+	/*
+	 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
+	 * at the next shadow byte to determine the type of the bad access.
+	 */
+	if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
+		shadow_addr++;
+
+	switch (*shadow_addr) {
+	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
+		/*
+		 * In theory it's still possible to see these shadow values
+		 * due to a data race in the kernel code.
+		 */
+		bug_type = "out-of-bounds";
+		break;
+	case KASAN_PAGE_REDZONE:
+	case KASAN_KMALLOC_REDZONE:
+		bug_type = "slab-out-of-bounds";
+		break;
+	case KASAN_GLOBAL_REDZONE:
+		bug_type = "global-out-of-bounds";
+		break;
+	case KASAN_STACK_LEFT:
+	case KASAN_STACK_MID:
+	case KASAN_STACK_RIGHT:
+	case KASAN_STACK_PARTIAL:
+		bug_type = "stack-out-of-bounds";
+		break;
+	case KASAN_FREE_PAGE:
+	case KASAN_KMALLOC_FREE:
+		bug_type = "use-after-free";
+		break;
+	case KASAN_USE_AFTER_SCOPE:
+		bug_type = "use-after-scope";
+		break;
+	case KASAN_ALLOCA_LEFT:
+	case KASAN_ALLOCA_RIGHT:
+		bug_type = "alloca-out-of-bounds";
+		break;
+	}
+
+	return bug_type;
+}
+
+static const char *get_wild_bug_type(struct kasan_access_info *info)
+{
+	const char *bug_type = "unknown-crash";
+
+	if ((unsigned long)info->access_addr < PAGE_SIZE)
+		bug_type = "null-ptr-deref";
+	else if ((unsigned long)info->access_addr < TASK_SIZE)
+		bug_type = "user-memory-access";
+	else
+		bug_type = "wild-memory-access";
+
+	return bug_type;
+}
+
+const char *get_bug_type(struct kasan_access_info *info)
+{
+	if (addr_has_shadow(info->access_addr))
+		return get_shadow_bug_type(info);
+	return get_wild_bug_type(info);
+}
+
+#define DEFINE_ASAN_REPORT_LOAD(size)                     \
+void __asan_report_load##size##_noabort(unsigned long addr) \
+{                                                         \
+	kasan_report(addr, size, false, _RET_IP_);	  \
+}                                                         \
+EXPORT_SYMBOL(__asan_report_load##size##_noabort)
+
+#define DEFINE_ASAN_REPORT_STORE(size)                     \
+void __asan_report_store##size##_noabort(unsigned long addr) \
+{                                                          \
+	kasan_report(addr, size, true, _RET_IP_);	   \
+}                                                          \
+EXPORT_SYMBOL(__asan_report_store##size##_noabort)
+
+DEFINE_ASAN_REPORT_LOAD(1);
+DEFINE_ASAN_REPORT_LOAD(2);
+DEFINE_ASAN_REPORT_LOAD(4);
+DEFINE_ASAN_REPORT_LOAD(8);
+DEFINE_ASAN_REPORT_LOAD(16);
+DEFINE_ASAN_REPORT_STORE(1);
+DEFINE_ASAN_REPORT_STORE(2);
+DEFINE_ASAN_REPORT_STORE(4);
+DEFINE_ASAN_REPORT_STORE(8);
+DEFINE_ASAN_REPORT_STORE(16);
+
+void __asan_report_load_n_noabort(unsigned long addr, size_t size)
+{
+	kasan_report(addr, size, false, _RET_IP_);
+}
+EXPORT_SYMBOL(__asan_report_load_n_noabort);
+
+void __asan_report_store_n_noabort(unsigned long addr, size_t size)
+{
+	kasan_report(addr, size, true, _RET_IP_);
+}
+EXPORT_SYMBOL(__asan_report_store_n_noabort);

mm/kasan/kasan.h

@@ -109,11 +109,18 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
 		<< KASAN_SHADOW_SCALE_SHIFT);
 }
 
+static inline bool addr_has_shadow(const void *addr)
+{
+	return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
+}
+
 void kasan_poison_shadow(const void *address, size_t size, u8 value);
 
 void check_memory_region(unsigned long addr, size_t size, bool write,
 				unsigned long ret_ip);
 
+const char *get_bug_type(struct kasan_access_info *info);
+
 void kasan_report(unsigned long addr, size_t size,
 		bool is_write, unsigned long ip);
 void kasan_report_invalid_free(void *object, unsigned long ip);