+ mm-kfence-fix-false-positives-on-big-endian.patch added to mm-hotfixes-unstable branch

+ mm-kfence-fix-false-positives-on-big-endian.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: kfence: fix false positives on big endian
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-kfence-fix-false-positives-on-big-endian.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kfence-fix-false-positives-on-big-endian.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Michael Ellerman <mpe@ellerman.id.au>
Subject: mm: kfence: fix false positives on big endian
Date: Fri, 5 May 2023 13:51:27 +1000

Since commit 1ba3cbf3ec3b ("mm: kfence: improve the performance of
__kfence_alloc() and __kfence_free()"), kfence reports failures in random
places at boot on big endian machines.

The problem is that the new KFENCE_CANARY_PATTERN_U64 encodes the address
of each byte in its value, so it needs to be byte swapped on big endian
machines.

The compiler is smart enough to do the le64_to_cpu() at compile time, so
there is no runtime overhead.

Link: https://lkml.kernel.org/r/20230505035127.195387-1-mpe@ellerman.id.au
Fixes: 1ba3cbf3ec3b ("mm: kfence: improve the performance of __kfence_alloc() and __kfence_free()")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kfence/kfence.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/kfence/kfence.h~mm-kfence-fix-false-positives-on-big-endian
+++ a/mm/kfence/kfence.h
@@ -29,7 +29,7 @@
  * canary of every 8 bytes is the same. 64-bit memory can be filled and checked
  * at a time instead of byte by byte to improve performance.
  */
-#define KFENCE_CANARY_PATTERN_U64 ((u64)0xaaaaaaaaaaaaaaaa ^ (u64)(0x0706050403020100))
+#define KFENCE_CANARY_PATTERN_U64 ((u64)0xaaaaaaaaaaaaaaaa ^ (u64)(le64_to_cpu(0x0706050403020100)))
 
 /* Maximum stack depth for reports. */
 #define KFENCE_STACK_DEPTH 64
_

Patches currently in -mm which might be from mpe@ellerman.id.au are

mm-kfence-fix-false-positives-on-big-endian.patch