The patch titled
Subject: mm: kfence: fix using kfence_metadata without initialization in show_object()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-kfence-fix-using-kfence_metadata-without-initialization-in-show_object.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-using-kfence_metadata-without-initialization-in-show_object.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: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: kfence: fix using kfence_metadata without initialization in show_object()
Date: Wed, 15 Mar 2023 11:44:41 +0800
The variable kfence_metadata is initialized in kfence_init_pool(), then,
it is not initialized if kfence is disabled after booting. In this case,
kfence_metadata will be used (e.g. ->lock and ->state fields) without
initialization when reading /sys/kernel/debug/kfence/objects. There will
be a warning if you enable CONFIG_DEBUG_SPINLOCK. Fix it by creating
debugfs files when necessary.
Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@xxxxxxxxxxxxx
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Tested-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: SeongJae Park <sjpark@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kfence/core.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
--- a/mm/kfence/core.c~mm-kfence-fix-using-kfence_metadata-without-initialization-in-show_object
+++ a/mm/kfence/core.c
@@ -726,10 +726,14 @@ static const struct seq_operations objec
};
DEFINE_SEQ_ATTRIBUTE(objects);
-static int __init kfence_debugfs_init(void)
+static int kfence_debugfs_init(void)
{
- struct dentry *kfence_dir = debugfs_create_dir("kfence", NULL);
+ struct dentry *kfence_dir;
+ if (!READ_ONCE(kfence_enabled))
+ return 0;
+
+ kfence_dir = debugfs_create_dir("kfence", NULL);
debugfs_create_file("stats", 0444, kfence_dir, NULL, &stats_fops);
debugfs_create_file("objects", 0400, kfence_dir, NULL, &objects_fops);
return 0;
@@ -883,6 +887,8 @@ static int kfence_init_late(void)
}
kfence_init_enable();
+ kfence_debugfs_init();
+
return 0;
}
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-kfence-fix-using-kfence_metadata-without-initialization-in-show_object.patch
mm-hugetlb_vmemmap-simplify-hugetlb_vmemmap_init-a-bit.patch
