+ kasan-add-bug-reporting-routines-for-tag-based-mode.patch added to -mm tree

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The patch titled
     Subject: kasan: add bug reporting routines for tag-based mode
has been added to the -mm tree.  Its filename is
     kasan-add-bug-reporting-routines-for-tag-based-mode.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/kasan-add-bug-reporting-routines-for-tag-based-mode.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/kasan-add-bug-reporting-routines-for-tag-based-mode.patch

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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan: add bug reporting routines for tag-based mode

This commit adds rountines, that print tag-based KASAN error reports.
Those are quite similar to generic KASAN, the difference is:

1. The way tag-based KASAN finds the first bad shadow cell (with a
   mismatching tag). Tag-based KASAN compares memory tags from the shadow
   memory to the pointer tag.

2. Tag-based KASAN reports all bugs with the "KASAN: invalid-access"
   header.

Also simplify generic KASAN find_first_bad_addr.

Link: http://lkml.kernel.org/r/996c09ec2c8f11294c106973f3b1a211417fa74e.1543337629.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---


--- a/mm/kasan/generic_report.c~kasan-add-bug-reporting-routines-for-tag-based-mode
+++ a/mm/kasan/generic_report.c
@@ -33,16 +33,13 @@
 #include "kasan.h"
 #include "../slab.h"
 
-static const void *find_first_bad_addr(const void *addr, size_t size)
+void *find_first_bad_addr(void *addr, size_t size)
 {
-	u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
-	const void *first_bad_addr = addr;
+	void *p = 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;
+	while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
+		p += KASAN_SHADOW_SCALE_SIZE;
+	return p;
 }
 
 static const char *get_shadow_bug_type(struct kasan_access_info *info)
@@ -50,9 +47,6 @@ static const char *get_shadow_bug_type(s
 	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);
 
 	/*
--- a/mm/kasan/kasan.h~kasan-add-bug-reporting-routines-for-tag-based-mode
+++ a/mm/kasan/kasan.h
@@ -119,6 +119,7 @@ void kasan_poison_shadow(const void *add
 void check_memory_region(unsigned long addr, size_t size, bool write,
 				unsigned long ret_ip);
 
+void *find_first_bad_addr(void *addr, size_t size);
 const char *get_bug_type(struct kasan_access_info *info);
 
 void kasan_report(unsigned long addr, size_t size,
@@ -139,10 +140,14 @@ static inline void quarantine_remove_cac
 
 #ifdef CONFIG_KASAN_SW_TAGS
 
+void print_tags(u8 addr_tag, const void *addr);
+
 u8 random_tag(void);
 
 #else
 
+static inline void print_tags(u8 addr_tag, const void *addr) { }
+
 static inline u8 random_tag(void)
 {
 	return 0;
--- a/mm/kasan/report.c~kasan-add-bug-reporting-routines-for-tag-based-mode
+++ a/mm/kasan/report.c
@@ -64,11 +64,10 @@ static int __init kasan_set_multi_shot(c
 }
 __setup("kasan_multi_shot", kasan_set_multi_shot);
 
-static void print_error_description(struct kasan_access_info *info,
-					const char *bug_type)
+static void print_error_description(struct kasan_access_info *info)
 {
 	pr_err("BUG: KASAN: %s in %pS\n",
-		bug_type, (void *)info->ip);
+		get_bug_type(info), (void *)info->ip);
 	pr_err("%s of size %zu at addr %px by task %s/%d\n",
 		info->is_write ? "Write" : "Read", info->access_size,
 		info->access_addr, current->comm, task_pid_nr(current));
@@ -272,6 +271,8 @@ void kasan_report_invalid_free(void *obj
 
 	start_report(&flags);
 	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
+	print_tags(get_tag(object), reset_tag(object));
+	object = reset_tag(object);
 	pr_err("\n");
 	print_address_description(object);
 	pr_err("\n");
@@ -279,41 +280,45 @@ void kasan_report_invalid_free(void *obj
 	end_report(&flags);
 }
 
-static void kasan_report_error(struct kasan_access_info *info)
-{
-	unsigned long flags;
-
-	start_report(&flags);
-
-	print_error_description(info, get_bug_type(info));
-	pr_err("\n");
-
-	if (!addr_has_shadow(info->access_addr)) {
-		dump_stack();
-	} else {
-		print_address_description((void *)info->access_addr);
-		pr_err("\n");
-		print_shadow_for_address(info->first_bad_addr);
-	}
-
-	end_report(&flags);
-}
-
 void kasan_report(unsigned long addr, size_t size,
 		bool is_write, unsigned long ip)
 {
 	struct kasan_access_info info;
+	void *tagged_addr;
+	void *untagged_addr;
+	unsigned long flags;
 
 	if (likely(!report_enabled()))
 		return;
 
 	disable_trace_on_warning();
 
-	info.access_addr = (void *)addr;
-	info.first_bad_addr = (void *)addr;
+	tagged_addr = (void *)addr;
+	untagged_addr = reset_tag(tagged_addr);
+
+	info.access_addr = tagged_addr;
+	if (addr_has_shadow(untagged_addr))
+		info.first_bad_addr = find_first_bad_addr(tagged_addr, size);
+	else
+		info.first_bad_addr = untagged_addr;
 	info.access_size = size;
 	info.is_write = is_write;
 	info.ip = ip;
 
-	kasan_report_error(&info);
+	start_report(&flags);
+
+	print_error_description(&info);
+	if (addr_has_shadow(untagged_addr))
+		print_tags(get_tag(tagged_addr), info.first_bad_addr);
+	pr_err("\n");
+
+	if (addr_has_shadow(untagged_addr)) {
+		print_address_description(untagged_addr);
+		pr_err("\n");
+		print_shadow_for_address(info.first_bad_addr);
+	} else {
+		dump_stack();
+	}
+
+	end_report(&flags);
 }
--- a/mm/kasan/tags_report.c~kasan-add-bug-reporting-routines-for-tag-based-mode
+++ a/mm/kasan/tags_report.c
@@ -37,3 +37,21 @@ const char *get_bug_type(struct kasan_ac
 {
 	return "invalid-access";
 }
+
+void *find_first_bad_addr(void *addr, size_t size)
+{
+	u8 tag = get_tag(addr);
+	void *p = reset_tag(addr);
+	void *end = p + size;
+
+	while (p < end && tag == *(u8 *)kasan_mem_to_shadow(p))
+		p += KASAN_SHADOW_SCALE_SIZE;
+	return p;
+}
+
+void print_tags(u8 addr_tag, const void *addr)
+{
+	u8 *shadow = (u8 *)kasan_mem_to_shadow(addr);
+
+	pr_err("Pointer tag: [%02x], memory tag: [%02x]\n", addr_tag, *shadow);
+}
_

Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are

kasan-mm-change-hooks-signatures.patch
kasan-slub-handle-pointer-tags-in-early_kmem_cache_node_alloc.patch
kasan-move-common-generic-and-tag-based-code-to-commonc.patch
kasan-rename-source-files-to-reflect-the-new-naming-scheme.patch
kasan-add-config_kasan_generic-and-config_kasan_sw_tags.patch
kasan-arm64-adjust-shadow-size-for-tag-based-mode.patch
kasan-rename-kasan_zero_page-to-kasan_early_shadow_page.patch
kasan-initialize-shadow-to-0xff-for-tag-based-mode.patch
arm64-move-untagged_addr-macro-from-uaccessh-to-memoryh.patch
kasan-add-tag-related-helper-functions.patch
kasan-arm64-untag-address-in-_virt_addr_is_linear.patch
kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu.patch
kasan-arm64-fix-up-fault-handling-logic.patch
kasan-arm64-enable-top-byte-ignore-for-the-kernel.patch
kasan-mm-perform-untagged-pointers-comparison-in-krealloc.patch
kasan-split-out-generic_reportc-from-reportc.patch
kasan-add-bug-reporting-routines-for-tag-based-mode.patch
mm-move-obj_to_index-to-include-linux-slab_defh.patch
kasan-add-hooks-implementation-for-tag-based-mode.patch
kasan-arm64-add-brk-handler-for-inline-instrumentation.patch
kasan-mm-arm64-tag-non-slab-memory-allocated-via-pagealloc.patch
kasan-add-__must_check-annotations-to-kasan-hooks.patch
kasan-arm64-select-have_arch_kasan_sw_tags.patch
kasan-update-documentation.patch
kasan-add-spdx-license-identifier-mark-to-source-files.patch




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