kasan: introduce complete_report_info

Introduce a complete_report_info() function that fills in the
first_bad_addr field of kasan_report_info instead of doing it in
kasan_report_*().

This function will be extended in the next patch.

Link: https://lkml.kernel.org/r/8eb1a9bd01f5d31eab4524da54a101b8720b469e.1662411799.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kasan/kasan.h

@@ -153,12 +153,15 @@ enum kasan_report_type {
 };
 
 struct kasan_report_info {
+	/* Filled in by kasan_report_*(). */
 	enum kasan_report_type type;
 	void *access_addr;
-	void *first_bad_addr;
 	size_t access_size;
 	bool is_write;
 	unsigned long ip;
+
+	/* Filled in by the common reporting code. */
+	void *first_bad_addr;
 };
 
 /* Do not change the struct layout: compiler ABI. */

mm/kasan/report.c

@@ -413,6 +413,17 @@ static void print_report(struct kasan_report_info *info)
 	}
 }
 
+static void complete_report_info(struct kasan_report_info *info)
+{
+	void *addr = kasan_reset_tag(info->access_addr);
+
+	if (info->type == KASAN_REPORT_ACCESS)
+		info->first_bad_addr = kasan_find_first_bad_addr(
+					info->access_addr, info->access_size);
+	else
+		info->first_bad_addr = addr;
+}
+
 void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type)
 {
 	unsigned long flags;
@@ -430,11 +441,12 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_ty
 
 	info.type = type;
 	info.access_addr = ptr;
-	info.first_bad_addr = kasan_reset_tag(ptr);
 	info.access_size = 0;
 	info.is_write = false;
 	info.ip = ip;
 
+	complete_report_info(&info);
+
 	print_report(&info);
 
 	end_report(&flags, ptr);
@@ -463,11 +475,12 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
 
 	info.type = KASAN_REPORT_ACCESS;
 	info.access_addr = ptr;
-	info.first_bad_addr = kasan_find_first_bad_addr(ptr, size);
 	info.access_size = size;
 	info.is_write = is_write;
 	info.ip = ip;
 
+	complete_report_info(&info);
+
 	print_report(&info);
 
 	end_report(&irq_flags, ptr);