From nobody Fri Jun 12 12:47:03 2026 Received: from out203-205-221-190.mail.qq.com (out203-205-221-190.mail.qq.com [203.205.221.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6F583CB918; Fri, 15 May 2026 04:32:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.205.221.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778819550; cv=none; b=sIe8bIbbrT8PhI6KSV0GQok6w/ZbHQKllYQ7WnvnjavZNHToZtJ8+KEv4yX/iCOCyDoAJ/c7hhpwkIG/v/o+Dy9dbHav5oHN5g4o8bv1lpL3i6P5PvmK8N84XlYWSTF6RMsHppz3XzNOdB1/5lV/CzxGrcBozFlufVFI/CxbUoE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778819550; c=relaxed/simple; bh=TYSeRGYQbwHjHYALMSLDJsZJO/7cPbMhBmvBCixaZIY=; h=Message-ID:From:To:Cc:Subject:Date:MIME-Version; b=OEHYhE016Ljf3+1yWpUklHsLqjmkzm55rtwyV0TD3cuaUloeROo8ALELpstXztHK17jRLzco78duMBo801lqNCU4VrvLDRPWIr529lc/qJx9vnrWSj2hdTq9PCCGXRySuIH6+HuYaixwV/VqHvvkKuv2Uk3z2wO9FjYj5jzOMaM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=foxmail.com; spf=pass smtp.mailfrom=foxmail.com; dkim=pass (1024-bit key) header.d=foxmail.com header.i=@foxmail.com header.b=dFHQa0JC; arc=none smtp.client-ip=203.205.221.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=foxmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=foxmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=foxmail.com header.i=@foxmail.com header.b="dFHQa0JC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foxmail.com; s=s201512; t=1778819545; bh=YLl7q1MmYPzGhWnNmRQA7+w/Oq/fXDObxmGFJVxbJ/E=; h=From:To:Cc:Subject:Date; b=dFHQa0JCnJik5vFFiKJiiECx1QLsMiTKuAfjAcAx38sgXiry3M4LeMPAcoKS5Hb6J VPd+MKeCrVm/TGJYIbW9RqGYOLIQ5kQzx3kXfcgPbKr2Jtx0oc4TdKHRfD3PRsx7H9 6Ici4tRpOxFgaZzJcDxoMQGrDKIdpvo/O+SbNtAE= Received: from China-team ([183.241.54.211]) by newxmesmtplogicsvrszb43-0.qq.com (NewEsmtp) with SMTP id 7EA09032; Fri, 15 May 2026 12:31:42 +0800 X-QQ-mid: xmsmtpt1778819502tpu0ief7s Message-ID: X-QQ-XMAILINFO: OIJV+wUmQOUAU1Gny1w7wbCvqHKx80R4MHaUEKQyN60xexAtVPINlb/uKfu0J3 RSIW1w1MUcsVRtAvimicxykfkg91+8SAkfwbZcEHgKVcR0CHFm3ciNhr0usYeaEllR5ejGgGfXHX TL5Zxdn7lP/X33Hsq/aAWUaI4xshOUe8NiOW8dkbXt/4doSo+1kKrS4BT2+y+BSqNnTlUV/Av+KY XAH/vnqx5m2nlyCdthIAPL4xp/YN3FRvqngpTQ/POYIqp9MXhtefAq2oHCo2pPZg0Fz6nHAjTg9B eoNNWcoXYoxoB1dAo0JPv35NqhDZT2ow9I53s5uYlFM9dmkV3DIDCySPkN+A4EYGBPemgSgq+XPI 0KJrr0FUUBy4MNYDQ4rFmZ8Yv6E8au7kEyy3+0K/wbFIGI3GDPCYtQD1EKC1C04Et17J8h8Jbybq 1O1kKoTdtq3fe5Ji8eJ71mG5U7+E7htJzzo9LqXUtnIef3CumME0Wr2FW6NVBjjcxnqHGLDDgNzK 7jTDlSV7hCDYvEwQ50zvr1UKPYf8DCG03cavH8/eZRspFpN+r7AuxFOW7mkdITMM7wCTDfAYQzMb iLGqxOE1xT/N1yPRpcxIPNTz4m0+yvONiTCkpIUb/3YoSjittLO2dwZl62Eg3XLzMrHU+PtKAcTb Eoai1M7kz6AboOXMY3uFtVhFhZ5p+sUnSO71V/7r2uUkLNd2JDM8d/o/sk/g8bObB2vtIZtJcTde 0to+bOBEcPIXwRt5xUBDDaSgdiTbtm8hkL+soHBGd1k9qhEYNq1aUVLKQJA5sUuxg3biGpPMaHRk mJOqOh1nEYou1v7LyabMzmm/zxrHmJk86ZKBaO2aUoMEJltFOXfvwpw9/RJGkeyDMP9maTdYCVMu 4iKwTpY4D7FSyKkIyI3fDnpi7rh/1RtzZNfVEkU2lH5h+eaxSsoNx6+uUuPwbTjCGiY2EI5yu65n Ssr7I0N2UFTSBg57gZzR/hGX6DG8P+TIHF+uaX1NfgjP3QdEAU4cOjnHZK75FcD7VKugQ4MD77bG 7iz1ZeTjBIcDEsQSitaRsdZOd53zK9FsxaPvaXJQekjA8YlC5hgxIbkaacvv30/YL2IUrwxw== X-QQ-XMRINFO: NS+P29fieYNwqS3WCnRCOn9D1NpZuCnCRA== From: Alva Lan To: gregkh@linuxfoundation.org, sashal@kernel.org, stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Namjae Jeon , munan Huang , ChenXiaoSong , Steve French , Alva Lan Subject: [PATCH 6.6.y] ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger Date: Fri, 15 May 2026 12:31:24 +0800 X-OQ-MSGID: <20260515043124.728-1-alvalan9@foxmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Namjae Jeon [ Upstream commit 235e32320a470fcd3998fb3774f2290a0eb302a1 ] When a durable file handle survives session disconnect (TCP close without SMB2_LOGOFF), session_fd_check() sets fp->conn =3D NULL to preserve the handle for later reconnection. However, it did not clean up the byte-range locks on fp->lock_list. Later, when the durable scavenger thread times out and calls __ksmbd_close_fd(NULL, fp), the lock cleanup loop did: spin_lock(&fp->conn->llist_lock); This caused a slab use-after-free because fp->conn was NULL and the original connection object had already been freed by ksmbd_tcp_disconnect(). The root cause is asymmetric cleanup: lock entries (smb_lock->clist) were left dangling on the freed conn->lock_list while fp->conn was nulled out. To fix this issue properly, we need to handle the lifetime of smb_lock->clist across three paths: - Safely skip clist deletion when list is empty and fp->conn is NULL. - Remove the lock from the old connection's lock_list in session_fd_check() - Re-add the lock to the new connection's lock_list in ksmbd_reopen_durable_fd(). Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Co-developed-by: munan Huang Signed-off-by: munan Huang Reviewed-by: ChenXiaoSong Signed-off-by: Namjae Jeon Signed-off-by: Steve French [ Minor context conflict resolved. ] Signed-off-by: Alva Lan --- Backport notes: - Minor context conflict in vfs_cache.c in 6.6.y. This only affects surrounding context lines, not the fix logic itself. - Tested with KASAN-enabled kernel: fixed kernel shows no crash when durable handle with byte-range lock is expired by scavenger after abrupt TCP disconnect. --- fs/smb/server/vfs_cache.c | 40 +++++++++++++++++++++++++++++---------- 1 file changed, 30 insertions(+), 10 deletions(-) diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index 2fcb7ca33a63..eacc6ef41db0 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -356,9 +356,11 @@ static void __ksmbd_close_fd(struct ksmbd_file_table *= ft, struct ksmbd_file *fp) * there are not accesses to fp->lock_list. */ list_for_each_entry_safe(smb_lock, tmp_lock, &fp->lock_list, flist) { - spin_lock(&fp->conn->llist_lock); - list_del(&smb_lock->clist); - spin_unlock(&fp->conn->llist_lock); + if (!list_empty(&smb_lock->clist) && fp->conn) { + spin_lock(&fp->conn->llist_lock); + list_del(&smb_lock->clist); + spin_unlock(&fp->conn->llist_lock); + } =20 list_del(&smb_lock->flist); locks_free_lock(smb_lock->fl); @@ -755,6 +757,7 @@ static bool session_fd_check(struct ksmbd_tree_connect = *tcon, struct ksmbd_inode *ci; struct oplock_info *op; struct ksmbd_conn *conn; + struct ksmbd_lock *smb_lock, *tmp_lock; =20 if (!is_reconnectable(fp)) return false; @@ -771,6 +774,12 @@ static bool session_fd_check(struct ksmbd_tree_connect= *tcon, } up_write(&ci->m_lock); =20 + list_for_each_entry_safe(smb_lock, tmp_lock, &fp->lock_list, flist) { + spin_lock(&fp->conn->llist_lock); + list_del_init(&smb_lock->clist); + spin_unlock(&fp->conn->llist_lock); + } + fp->conn =3D NULL; fp->tcon =3D NULL; fp->volatile_id =3D KSMBD_NO_FID; @@ -844,6 +853,9 @@ int ksmbd_reopen_durable_fd(struct ksmbd_work *work, st= ruct ksmbd_file *fp) { struct ksmbd_inode *ci; struct oplock_info *op; + struct ksmbd_conn *conn =3D work->conn; + struct ksmbd_lock *smb_lock; + unsigned int old_f_state; =20 if (!fp->is_durable || fp->conn || fp->tcon) { pr_err("Invalid durable fd [%p:%p]\n", fp->conn, fp->tcon); @@ -855,9 +867,23 @@ int ksmbd_reopen_durable_fd(struct ksmbd_work *work, s= truct ksmbd_file *fp) return -EBADF; } =20 - fp->conn =3D work->conn; + old_f_state =3D fp->f_state; + fp->f_state =3D FP_NEW; + __open_id(&work->sess->file_table, fp, OPEN_ID_TYPE_VOLATILE_ID); + if (!has_file_id(fp->volatile_id)) { + fp->f_state =3D old_f_state; + return -EBADF; + } + + fp->conn =3D conn; fp->tcon =3D work->tcon; =20 + list_for_each_entry(smb_lock, &fp->lock_list, flist) { + spin_lock(&conn->llist_lock); + list_add_tail(&smb_lock->clist, &conn->lock_list); + spin_unlock(&conn->llist_lock); + } + ci =3D fp->f_ci; down_write(&ci->m_lock); list_for_each_entry_rcu(op, &ci->m_op_list, op_entry) { @@ -868,12 +894,6 @@ int ksmbd_reopen_durable_fd(struct ksmbd_work *work, s= truct ksmbd_file *fp) } up_write(&ci->m_lock); =20 - __open_id(&work->sess->file_table, fp, OPEN_ID_TYPE_VOLATILE_ID); - if (!has_file_id(fp->volatile_id)) { - fp->conn =3D NULL; - fp->tcon =3D NULL; - return -EBADF; - } return 0; } =20 --=20 2.43.0