[merged mm-stable] mm-kfence-disable-kmsan-when-checking-the-canary.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
Subject: mm: kfence: disable KMSAN when checking the canary
has been removed from the -mm tree. Its filename was
mm-kfence-disable-kmsan-when-checking-the-canary.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Ilya Leoshkevich <i...@linux.ibm.com>
Subject: mm: kfence: disable KMSAN when checking the canary
Date: Fri, 21 Jun 2024 13:35:03 +0200

KMSAN warns about check_canary() accessing the canary.

The reason is that, even though set_canary() is properly instrumented and
sets shadow, slub explicitly poisons the canary's address range
afterwards.

Unpoisoning the canary is not the right thing to do: only check_canary()
is supposed to ever touch it. Instead, disable KMSAN checks around canary
read accesses.

Link: https://lkml.kernel.org/r/20240621113706...@linux.ibm.com
Signed-off-by: Ilya Leoshkevich <i...@linux.ibm.com>
Reviewed-by: Alexander Potapenko <gli...@google.com>
Tested-by: Alexander Potapenko <gli...@google.com>
Cc: Alexander Gordeev <agor...@linux.ibm.com>
Cc: Christian Borntraeger <bornt...@linux.ibm.com>
Cc: Christoph Lameter <c...@linux.com>
Cc: David Rientjes <rien...@google.com>
Cc: Dmitry Vyukov <dvy...@google.com>
Cc: Heiko Carstens <h...@linux.ibm.com>
Cc: Hyeonggon Yoo <42.h...@gmail.com>
Cc: Joonsoo Kim <iamjoon...@lge.com>
Cc: <kasa...@googlegroups.com>
Cc: Marco Elver <el...@google.com>
Cc: Mark Rutland <mark.r...@arm.com>
Cc: Masami Hiramatsu (Google) <mhir...@kernel.org>
Cc: Pekka Enberg <pen...@kernel.org>
Cc: Roman Gushchin <roman.g...@linux.dev>
Cc: Steven Rostedt (Google) <ros...@goodmis.org>
Cc: Sven Schnelle <sv...@linux.ibm.com>
Cc: Vasily Gorbik <g...@linux.ibm.com>
Cc: Vlastimil Babka <vba...@suse.cz>
Signed-off-by: Andrew Morton <ak...@linux-foundation.org>
---

mm/kfence/core.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/mm/kfence/core.c~mm-kfence-disable-kmsan-when-checking-the-canary
+++ a/mm/kfence/core.c
@@ -305,8 +305,14 @@ metadata_update_state(struct kfence_meta
WRITE_ONCE(meta->state, next);
}

+#ifdef CONFIG_KMSAN
+#define check_canary_attributes noinline __no_kmsan_checks
+#else
+#define check_canary_attributes inline
+#endif
+
/* Check canary byte at @addr. */
-static inline bool check_canary_byte(u8 *addr)
+static check_canary_attributes bool check_canary_byte(u8 *addr)
{
struct kfence_metadata *meta;
unsigned long flags;
@@ -341,7 +347,8 @@ static inline void set_canary(const stru
*((u64 *)addr) = KFENCE_CANARY_PATTERN_U64;
}

-static inline void check_canary(const struct kfence_metadata *meta)
+static check_canary_attributes void
+check_canary(const struct kfence_metadata *meta)
{
const unsigned long pageaddr = ALIGN_DOWN(meta->addr, PAGE_SIZE);
unsigned long addr = pageaddr;
_

Patches currently in -mm which might be from i...@linux.ibm.com are