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mm: kfence: fix using kfence_metadata without initialization in show_object()

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commit 1c86a188e0 upstream.

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@bytedance.com
Fixes: 0ce20dd840 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Tested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Muchun Song 2023-03-15 11:44:41 +08:00 committed by Greg Kroah-Hartman
parent 7a74603c24
commit 5229bb42fb
1 changed files with 6 additions and 2 deletions
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8
mm/kfence/core.c
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@ -678,10 +678,14 @@ static const struct file_operations objects_fops = {
.release = seq_release,
};
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;