Re: [PATCH v2 2/2] kasan, slub: reset tag when printing address

On Wed, 2021-08-04 at 10:41 +0200, Marco Elver wrote:

On Wed, 4 Aug 2021 at 10:23, Kuan-Ying Lee <
Kuan-Ying.Lee@mediatek.com> wrote:

quoted

The address still includes the tags when it is printed.
With hardware tag-based kasan enabled, we will get a
false positive KASAN issue when we access metadata.

Reset the tag before we access the metadata.

Fixes: aa1ef4d7b3f6 ("kasan, mm: reset tags when accessing
metadata")
Signed-off-by: Kuan-Ying Lee <redacted>
Suggested-by: Marco Elver <elver@google.com>

Note, in this case Suggested-by is inappropriate, because I did not
suggest the change in any way (you already had it in v1). I just
commented on the fact that it's missing a Fixes so stable can pick it
up and some clarification.

Reviewed-by: Marco Elver <elver@google.com>

Got it.
I will remove it on v3.
Thanks.

quoted

---
 mm/slub.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index b6c5205252eb..f77d8cd79ef7 100644
--- a/mm/slub.c
+++ b/mm/slub.c

@@ -576,8 +576,8 @@ static void print_section(char *level, char

*text, u8 *addr,
                          unsigned int length)
 {
        metadata_access_enable();
-       print_hex_dump(level, kasan_reset_tag(text),
DUMP_PREFIX_ADDRESS,
-                       16, 1, addr, length, 1);
+       print_hex_dump(level, text, DUMP_PREFIX_ADDRESS,
+                       16, 1, kasan_reset_tag((void *)addr),
length, 1);
        metadata_access_disable();
 }

--
2.18.0