From: Muchun Song <songmuchun@xxxxxxxxxxxxx> commit 1c86a188e03156223a34d09ce290b49bd4dd0403 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@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> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/kfence/core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -678,10 +678,14 @@ static const struct file_operations obje .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;
