kasan: simplify kasan_find_first_bad_addr call sites

Move the addr_has_metadata() check into kasan_find_first_bad_addr().

Link: https://lkml.kernel.org/r/a49576f7a23283d786ba61579cb0c5057e8f0b9b.1646237226.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/kasan/report.c

@@ -444,10 +444,7 @@ static void __kasan_report(void *addr, size_t size, bool is_write,
 	start_report(&flags, true);
 
 	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 = addr;
+	info.first_bad_addr = kasan_find_first_bad_addr(addr, size);
 	info.access_size = size;
 	info.is_write = is_write;
 	info.ip = ip;

mm/kasan/report_generic.c

@@ -34,8 +34,12 @@ void *kasan_find_first_bad_addr(void *addr, size_t size)
 {
 	void *p = addr;
 
+	if (!addr_has_metadata(p))
+		return p;
+
 	while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
 		p += KASAN_GRANULE_SIZE;
+
 	return p;
 }
 

mm/kasan/report_hw_tags.c

@@ -17,6 +17,7 @@
 
 void *kasan_find_first_bad_addr(void *addr, size_t size)
 {
+	/* Return the same value regardless of whether addr_has_metadata(). */
 	return kasan_reset_tag(addr);
 }
 

mm/kasan/report_sw_tags.c

@@ -36,8 +36,12 @@ void *kasan_find_first_bad_addr(void *addr, size_t size)
 	void *p = kasan_reset_tag(addr);
 	void *end = p + size;
 
+	if (!addr_has_metadata(p))
+		return p;
+
 	while (p < end && tag == *(u8 *)kasan_mem_to_shadow(p))
 		p += KASAN_GRANULE_SIZE;
+
 	return p;
 }