kasan: always taint kernel on report

Currently we already taint the kernel in some cases. E.g. if we hit some
bug in slub memory we call object_err() which will taint the kernel with
TAINT_BAD_PAGE flag. But for other kind of bugs kernel left untainted.

Always taint with TAINT_BAD_PAGE if kasan found some bug. This is useful
for automated testing.

Signed-off-by: Andrey Ryabinin <[e-mail]>
Cc: Alexander Potapenko <[e-mail]>
Reviewed-by: Dmitry Vyukov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

mm/kasan/report.c

···
 	}
 	pr_err("================================="
 		"=================================\n");
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irqrestore(&report_lock, flags);
 	kasan_enable_current();
 }