From 5229bb42fba253890cc7e8e67b891f7c9cc92b6e Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 15 Mar 2023 11:44:41 +0800 Subject: [PATCH] mm: kfence: fix using kfence_metadata without initialization in show_object() 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@bytedance.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song Tested-by: Marco Elver Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Jann Horn Cc: SeongJae Park Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/kfence/core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index d25202766fbb..3eab72fb3d8c 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -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;