linux-kernel - [PATCH mm 11/22] kasan: split out print_report from __kasan

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Date:   Wed,  2 Mar 2022 17:36:31 +0100
From:   andrey.konovalov@...ux.dev
To:     Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm 11/22] kasan: split out print_report from __kasan_report

From: Andrey Konovalov <andreyknvl@...gle.com>

Split out the part of __kasan_report() that prints things into
print_report(). One of the subsequent patches makes another error
handler use print_report() as well.

Includes lower-level changes:

- Allow addr_has_metadata() accepting a tagged address.
- Drop the const qualifier from the fields of kasan_access_info to avoid
  excessive type casts.
- Change the type of the address argument of __kasan_report() and
  end_report() to void * to reduce the number of type casts.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/kasan/kasan.h  |  7 +++---
 mm/kasan/report.c | 58 +++++++++++++++++++++++++----------------------
 2 files changed, 35 insertions(+), 30 deletions(-)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cc7162a9f304..40b863e289ec 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -128,8 +128,8 @@ static inline bool kasan_sync_fault_possible(void)
 #define META_ROWS_AROUND_ADDR 2
 
 struct kasan_access_info {
-	const void *access_addr;
-	const void *first_bad_addr;
+	void *access_addr;
+	void *first_bad_addr;
 	size_t access_size;
 	bool is_write;
 	unsigned long ip;
@@ -239,7 +239,8 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
 
 static inline bool addr_has_metadata(const void *addr)
 {
-	return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
+	return (kasan_reset_tag(addr) >=
+		kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
 }
 
 /**
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 9286ff6ae1a7..bb4c29b439b1 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -139,10 +139,11 @@ static void start_report(unsigned long *flags, bool sync)
 	pr_err("==================================================================\n");
 }
 
-static void end_report(unsigned long *flags, unsigned long addr)
+static void end_report(unsigned long *flags, void *addr)
 {
 	if (addr)
-		trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
+		trace_error_report_end(ERROR_DETECTOR_KASAN,
+				       (unsigned long)addr);
 	pr_err("==================================================================\n");
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irqrestore(&report_lock, *flags);
@@ -398,7 +399,7 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
 	pr_err("\n");
 	print_address_description(object, tag);
 	print_memory_metadata(object);
-	end_report(&flags, (unsigned long)object);
+	end_report(&flags, object);
 }
 
 #ifdef CONFIG_KASAN_HW_TAGS
@@ -411,44 +412,47 @@ void kasan_report_async(void)
 	pr_err("Asynchronous mode enabled: no access details available\n");
 	pr_err("\n");
 	dump_stack_lvl(KERN_ERR);
-	end_report(&flags, 0);
+	end_report(&flags, NULL);
 }
 #endif /* CONFIG_KASAN_HW_TAGS */
 
-static void __kasan_report(unsigned long addr, size_t size, bool is_write,
+static void print_report(struct kasan_access_info *info)
+{
+	void *tagged_addr = info->access_addr;
+	void *untagged_addr = kasan_reset_tag(tagged_addr);
+	u8 tag = get_tag(tagged_addr);
+
+	print_error_description(info);
+	if (addr_has_metadata(untagged_addr))
+		kasan_print_tags(tag, info->first_bad_addr);
+	pr_err("\n");
+
+	if (addr_has_metadata(untagged_addr)) {
+		print_address_description(untagged_addr, tag);
+		print_memory_metadata(info->first_bad_addr);
+	} else {
+		dump_stack_lvl(KERN_ERR);
+	}
+}
+
+static void __kasan_report(void *addr, size_t size, bool is_write,
 				unsigned long ip)
 {
 	struct kasan_access_info info;
-	void *tagged_addr;
-	void *untagged_addr;
 	unsigned long flags;
 
 	start_report(&flags, true);
 
-	tagged_addr = (void *)addr;
-	untagged_addr = kasan_reset_tag(tagged_addr);
-
-	info.access_addr = tagged_addr;
-	if (addr_has_metadata(untagged_addr))
-		info.first_bad_addr =
-			kasan_find_first_bad_addr(tagged_addr, size);
+	info.access_addr = addr;
+	if (addr_has_metadata(addr))
+		info.first_bad_addr = kasan_find_first_bad_addr(addr, size);
 	else
-		info.first_bad_addr = untagged_addr;
+		info.first_bad_addr = addr;
 	info.access_size = size;
 	info.is_write = is_write;
 	info.ip = ip;
 
-	print_error_description(&info);
-	if (addr_has_metadata(untagged_addr))
-		kasan_print_tags(get_tag(tagged_addr), info.first_bad_addr);
-	pr_err("\n");
-
-	if (addr_has_metadata(untagged_addr)) {
-		print_address_description(untagged_addr, get_tag(tagged_addr));
-		print_memory_metadata(info.first_bad_addr);
-	} else {
-		dump_stack_lvl(KERN_ERR);
-	}
+	print_report(&info);
 
 	end_report(&flags, addr);
 }
@@ -460,7 +464,7 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
 	bool ret = false;
 
 	if (likely(report_enabled())) {
-		__kasan_report(addr, size, is_write, ip);
+		__kasan_report((void *)addr, size, is_write, ip);
 		ret = true;
 	}
 
-- 
2.25.1