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/aee6897b1bd077732a315fd84c6b4f234dbfdfcb.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 33cc3b0e017e..82a23b23ff93 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -119,6 +119,7 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value);
 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_cache(struct kmem_cache *cache) { }
 
 #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;