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Fri, 09 Oct 2026 03:04:55 -0700 (PDT) From: Cen Zhang To: mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, akpm@linux-foundation.org, ghe@suse.com Cc: ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, jjzuming@gmail.com, zzzccc427@gmail.com Subject: [PATCH] ocfs2: Publish the filecheck owner before adding sysfs attributes Date: Fri, 9 Oct 2026 18:04:49 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ocfs2_filecheck_create_sysfs() initializes the filecheck allocation before calling kobject_init_and_add(), but assigns entry->fs_fcheck only after that call returns. The default attribute group can already be visible while registration is in progress. A concurrent read can therefore enter ocfs2_filecheck_attr_show() with a NULL fs_fcheck and try to lock its fc_lock. Assign the initialized owner before adding the kobject, so every activated attribute has valid state. Clear the pointer when addition fails, preserving the existing teardown guard and error cleanup. A controlled probe-instrumented test kernel with the original OCFS2 registration ordering produced this Oops during a concurrent sysfs read: KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] RIP: 0010:kasan_byte_accessible+0x15/0x30 Call Trace: __kasan_check_byte+0x13/0x50 lock_acquire+0x113/0x300 _raw_spin_lock+0x31/0x40 ocfs2_filecheck_attr_show+0x138/0x5f0 ocfs2_filecheck_show+0x5d/0x90 sysfs_kf_seq_show+0x1d3/0x360 seq_read_iter+0x480/0x1110 kernfs_fop_read_iter+0x419/0x5a0 vfs_read+0x7d2/0xc20 ksys_read+0x111/0x200 do_syscall_64+0x114/0x620 entry_SYSCALL_64_after_hwframe+0x77/0x7f Modules linked in: Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check") Assisted-by: LLM Signed-off-by: Cen Zhang --- fs/ocfs2/filecheck.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c index be713d7d24a76b9aa8fcded3d83b3d91d124eb6e..862c1ee7099c943b2e3e57e31f887380c6dc8a88 100644 --- a/fs/ocfs2/filecheck.c +++ b/fs/ocfs2/filecheck.c @@ -181,2 +181,4 @@ int ocfs2_filecheck_create_sysfs(struct ocfs2_super *osb) + /* Publish the initialized owner before activating its sysfs callbacks. */ + entry->fs_fcheck = fcheck; entry->fs_kobj.kset = osb->osb_dev_kset; @@ -186,2 +188,3 @@ int ocfs2_filecheck_create_sysfs(struct ocfs2_super *osb) if (ret) { + entry->fs_fcheck = NULL; kobject_put(&entry->fs_kobj); @@ -191,3 +194,2 @@ int ocfs2_filecheck_create_sysfs(struct ocfs2_super *osb) - entry->fs_fcheck = fcheck; return 0;