From e6e1db4fc7d0c1ff6ce5aaaef94344a012157473 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 16 Dec 2019 19:35:15 +0800 Subject: [PATCH] kernfs: fix ino wrap-around detection commit e23f568aa63f64cd6b355094224cc9356c0f696b upstream. When the 32bit ino wraps around, kernfs increments the generation number to distinguish reused ino instances. The wrap-around detection tests whether the allocated ino is lower than what the cursor but the cursor is pointing to the next ino to allocate so the condition never triggers. Fix it by remembering the last ino and comparing against that. Signed-off-by: Tejun Heo Reviewed-by: Greg Kroah-Hartman Fixes: 4a3ef68acacf ("kernfs: implement i_generation") Cc: Namhyung Kim Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- fs/kernfs/dir.c | 5 ++--- include/linux/kernfs.h | 1 + 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 853a69e493f5..a4a538abcaf9 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -624,7 +624,6 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, { struct kernfs_node *kn; u32 gen; - int cursor; int ret; name = kstrdup_const(name, GFP_KERNEL); @@ -637,11 +636,11 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, idr_preload(GFP_KERNEL); spin_lock(&kernfs_idr_lock); - cursor = idr_get_cursor(&root->ino_idr); ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC); - if (ret >= 0 && ret < cursor) + if (ret >= 0 && ret < root->last_ino) root->next_generation++; gen = root->next_generation; + root->last_ino = ret; spin_unlock(&kernfs_idr_lock); idr_preload_end(); if (ret < 0) diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 136ba4fba0b6..e7a24d45a717 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -192,6 +192,7 @@ struct kernfs_root { /* private fields, do not use outside kernfs proper */ struct idr ino_idr; + u32 last_ino; u32 next_generation; struct kernfs_syscall_ops *syscall_ops; -- GitLab