linux-kernel - [PATCH v2] kernfs: fix missing kernfs_idr

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Message-Id: <20230523024017.24851-1-songmuchun@bytedance.com>
Date:   Tue, 23 May 2023 10:40:17 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     gregkh@...uxfoundation.org, tj@...nel.org
Cc:     linux-kernel@...r.kernel.org, muchun.song@...ux.dev,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v2] kernfs: fix missing kernfs_idr_lock to remove an ID from the IDR

The root->ino_idr is supposed to be protected by kernfs_idr_lock, fix
it.

Fixes: 488dee96bb62 ("kernfs: allow creating kernfs objects with arbitrary uid/gid")
Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
v2:
 - Open code the locking.

 fs/kernfs/dir.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 45b6919903e6..5a1a4af9d3d2 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -655,7 +655,9 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 	return kn;
 
  err_out3:
+	spin_lock(&kernfs_idr_lock);
 	idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
+	spin_unlock(&kernfs_idr_lock);
  err_out2:
 	kmem_cache_free(kernfs_node_cache, kn);
  err_out1:
-- 
2.11.0