From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9551642188D; Wed, 4 Feb 2026 15:22:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770218563; cv=none; b=IiLzNMIGXSOSha7R890zskovmXjPasrJUlL3ccC/iMnhYlonqmpNF/8fvorQMh4SD10bw2JTXwj17LZrP39cictTHfQP0e4ubdZQ3dtI0nkLvk8hB2AcrZZXKwg5tXFwlSTYTa1M3S57CnJDRRZYx2jrEls3R/z5cx7fvQWU3z4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770218563; c=relaxed/simple; bh=bMkEpfz59UE83EY+szsmkWFahSkJl2VSp7ONwXjKPyI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NemaGdjUOq5JsUcobPvxAMoMGhOyb5Ew4unUfDW+cl6BdjEscVm/3Z8H8Q/8SgLOoXZgCHpmwaEQABrY5Oul0uHdUYqA7n4WC2+lGrFEGWkf1wcRJgnP19u2NLlqcdCbEhpdI0LTVzdsRo7YP5NysuI0WfM4hUUNMgfD7u/sq8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2lXyJui0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2lXyJui0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0497EC4CEF7; Wed, 4 Feb 2026 15:22:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770218563; bh=bMkEpfz59UE83EY+szsmkWFahSkJl2VSp7ONwXjKPyI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2lXyJui0KpC3PEZCtllnehAU9pUxb+P3MOLNopbrrcrkLx6bhkHaHtCEliZsNJzUF FPZ4xY1GtgJ7f2AAvcOZN/qDoDNyKeNRBAvH8E1q7YDkwgaFHp1WDJcknRjZ0fq/Ve rrAEETx8VXK1rYOEBtYWAhMglGXiLv3+SGHUscJk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marios Makassikis , Namjae Jeon , Steve French , Li hongliang <1468888505@139.com> Subject: [PATCH 6.6 67/72] ksmbd: fix recursive locking in RPC handle list access Date: Wed, 4 Feb 2026 15:41:10 +0100 Message-ID: <20260204143848.069797467@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260204143845.603454952@linuxfoundation.org> References: <20260204143845.603454952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marios Makassikis [ Upstream commit 88f170814fea74911ceab798a43cbd7c5599bed4 ] Since commit 305853cce3794 ("ksmbd: Fix race condition in RPC handle list access"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock. This causes hung connections / tasks when a client attempts to open a named pipe. Using Samba's rpcclient tool: $ rpcclient //192.168.1.254 -U user%password $ rpcclient $> srvinfo Kernel side: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000 Workqueue: ksmbd-io handle_ksmbd_work Call trace: __schedule from schedule+0x3c/0x58 schedule from schedule_preempt_disabled+0xc/0x10 schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8 rwsem_down_read_slowpath from down_read+0x28/0x30 down_read from ksmbd_session_rpc_method+0x18/0x3c ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68 ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228 ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8 create_smb2_pipe from smb2_open+0x10c/0x27ac smb2_open from handle_ksmbd_work+0x238/0x3dc handle_ksmbd_work from process_scheduled_works+0x160/0x25c process_scheduled_works from worker_thread+0x16c/0x1e8 worker_thread from kthread+0xa8/0xb8 kthread from ret_from_fork+0x14/0x38 Exception stack(0x8529ffb0 to 0x8529fff8) The task deadlocks because the lock is already held: ksmbd_session_rpc_open down_write(&sess->rpc_lock) ksmbd_rpc_open ksmbd_session_rpc_method down_read(&sess->rpc_lock) <-- deadlock Adjust ksmbd_session_rpc_method() callers to take the lock when necessary. Fixes: 305853cce3794 ("ksmbd: Fix race condition in RPC handle list access") Signed-off-by: Marios Makassikis Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Li hongliang <1468888505@139.com> Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/mgmt/user_session.c | 7 ++----- fs/smb/server/smb2pdu.c | 9 ++++++++- fs/smb/server/transport_ipc.c | 12 ++++++++++++ 3 files changed, 22 insertions(+), 6 deletions(-) --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -147,14 +147,11 @@ void ksmbd_session_rpc_close(struct ksmb int ksmbd_session_rpc_method(struct ksmbd_session *sess, int id) { struct ksmbd_session_rpc *entry; - int method; - down_read(&sess->rpc_lock); + lockdep_assert_held(&sess->rpc_lock); entry = xa_load(&sess->rpc_handle_list, id); - method = entry ? entry->method : 0; - up_read(&sess->rpc_lock); - return method; + return entry ? entry->method : 0; } void ksmbd_session_destroy(struct ksmbd_session *sess) --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -4614,8 +4614,15 @@ static int smb2_get_info_file_pipe(struc * pipe without opening it, checking error condition here */ id = req->VolatileFileId; - if (!ksmbd_session_rpc_method(sess, id)) + + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); + if (!ksmbd_session_rpc_method(sess, id)) { + up_read(&sess->rpc_lock); return -ENOENT; + } + up_read(&sess->rpc_lock); ksmbd_debug(SMB, "FileInfoClass %u, FileId 0x%llx\n", req->FileInfoClass, req->VolatileFileId); --- a/fs/smb/server/transport_ipc.c +++ b/fs/smb/server/transport_ipc.c @@ -778,6 +778,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_writ if (!msg) return NULL; + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); msg->type = KSMBD_EVENT_RPC_REQUEST; req = (struct ksmbd_rpc_command *)msg->payload; req->handle = handle; @@ -786,6 +789,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_writ req->flags |= KSMBD_RPC_WRITE_METHOD; req->payload_sz = payload_sz; memcpy(req->payload, payload, payload_sz); + up_read(&sess->rpc_lock); resp = ipc_msg_send_request(msg, req->handle); ipc_msg_free(msg); @@ -802,6 +806,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_read if (!msg) return NULL; + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); msg->type = KSMBD_EVENT_RPC_REQUEST; req = (struct ksmbd_rpc_command *)msg->payload; req->handle = handle; @@ -809,6 +816,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_read req->flags |= rpc_context_flags(sess); req->flags |= KSMBD_RPC_READ_METHOD; req->payload_sz = 0; + up_read(&sess->rpc_lock); resp = ipc_msg_send_request(msg, req->handle); ipc_msg_free(msg); @@ -829,6 +837,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioct if (!msg) return NULL; + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); msg->type = KSMBD_EVENT_RPC_REQUEST; req = (struct ksmbd_rpc_command *)msg->payload; req->handle = handle; @@ -837,6 +848,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioct req->flags |= KSMBD_RPC_IOCTL_METHOD; req->payload_sz = payload_sz; memcpy(req->payload, payload, payload_sz); + up_read(&sess->rpc_lock); resp = ipc_msg_send_request(msg, req->handle); ipc_msg_free(msg);