On Tue, 2021-07-27 at 09:20 +0200, Marco Elver wrote:

On Tue, 27 Jul 2021 at 06:00, Kuan-Ying Lee <
Kuan-Ying.Lee@mediatek.com> wrote:

quoted

Text is a string. We need to move this kasan_reset_tag()
to address but text.

Signed-off-by: Kuan-Ying Lee <redacted>

This patch also makes sense (I think), thanks for sending. But it's
unclear what the problem is. The fact that when the address is
printed
it still includes the tag? Or a false positive?
It'd be good to clarify in the commit message.

Yes, printed address includes the tag, so when we access the
metadata, we will encounter tag mismatch with HW tag-based kasan
enabled.

Here I'd also use a more descriptive patch title, something like
"kasan, slub: reset tag when printing address".

Also, I think this patch requires a:

  Fixes: aa1ef4d7b3f6 ("kasan, mm: reset tags when accessing
metadata")

So that stable kernels can pick this up if appropriate.

Thank you, Marco.
I will refine commit message in the v2.

quoted

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

diff --git a/mm/slub.c b/mm/slub.c
index 6dad2b6fda6f..d20674f839ba 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

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