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| author | Muchun Song <songmuchun@bytedance.com> | 2023-03-15 11:44:41 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-03-23 17:18:35 -0700 |
| commit | 1c86a188e03156223a34d09ce290b49bd4dd0403 (patch) | |
| tree | a5d6a977efb9fdb8aac4bf556d6acd93f0d2401f | |
| parent | 13684e966d46283e0e89b6a4941596dc52b18bf3 (diff) | |
| download | lwn-1c86a188e03156223a34d09ce290b49bd4dd0403.tar.gz lwn-1c86a188e03156223a34d09ce290b49bd4dd0403.zip | |
mm: kfence: fix using kfence_metadata without initialization in show_object()
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 <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>
| -rw-r--r-- | mm/kfence/core.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 5349c37a5dac..79c94ee55f97 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -726,10 +726,14 @@ static const struct seq_operations objects_sops = { }; 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; } |