From nobody Sun Feb 8 20:17:40 2026 Received: from n169-114.mail.139.com (n169-114.mail.139.com [120.232.169.114]) (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 3D14929B76F; Wed, 4 Feb 2026 02:22:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=120.232.169.114 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770171744; cv=none; b=TB06OCwO9qLfIuUqyuFHE1GTFQBiY2r40Do1Ppq7XDhASyl/Q52yXLekCy4iagcbd2mC4wViftGjgVVks+6uWnTaT2SGOIcuHHKnsYqTnwIQicFAnzSsmh1aXOOJdQdCpvEpT4DZkkSkgH3I4X5L7lRmRAupKlEQRbBoe9fQQlk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770171744; c=relaxed/simple; bh=q++V7uuIKNzI6SstRdiLpRLr8M2f7zydqlcGpzWMsPk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=Q0kMbUUF3cLi9d9c67F0GNxqkG3PsGxIRNjmUpPgU+8q3PlMCUEoQzQyXWji3ccBGmDfH/42+f5G4sTmAirJJbNfPkgpdU6wuwKY4YIHghkaQ1mPQpct4vPJLoYp+O/VYMA1W2//I9jnzjqQJL5rD06a+0eYppnMSvH1FJlM3s0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=139.com; spf=pass smtp.mailfrom=139.com; dkim=pass (1024-bit key) header.d=139.com header.i=@139.com header.b=CtGrCzBp; arc=none smtp.client-ip=120.232.169.114 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=139.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=139.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=139.com header.i=@139.com header.b="CtGrCzBp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=139.com; s=dkim; l=0; h=from:subject:message-id:to:cc:mime-version; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; b=CtGrCzBpoJiJIHMIgdb9Bo3Zt0BdoxDyoT6qXvvDbO1QxWcwuG0egvGlYJWXvSFZq53u/4GH1DAEm 0pk6W+1aDazWCtiyHoWbMgr3yIQ81sgoBN3FLsKb1N5tI4hBvOWIbl7I4nVn4BkbGcL4nkWv4SzihY 3O1MWinPvs/SqV5k= X-RM-TagInfo: emlType=0 X-RM-SPAM: X-RM-SPAM-FLAG: 00000000 Received: from NTT-kernel-dev (unknown[60.247.85.88]) by rmsmtp-lg-appmail-37-12051 (RichMail) with SMTP id 2f136982ada9798-017b6; Wed, 04 Feb 2026 10:23:41 +0800 (CST) X-RM-TRANSID: 2f136982ada9798-017b6 From: Li hongliang <1468888505@139.com> To: mmakassikis@freebox.fr, gregkh@linuxfoundation.org, stable@vger.kernel.org, ysk@kzalloc.com Cc: patches@lists.linux.dev, linux-kernel@vger.kernel.org, linkinjeon@kernel.org, sfrench@samba.org, senozhatsky@chromium.org, tom@talpey.com, akendo@akendo.eu, set_pte_at@outlook.com, linux-cifs@vger.kernel.org, stfrench@microsoft.com Subject: [PATCH 6.6.y] ksmbd: fix recursive locking in RPC handle list access Date: Wed, 4 Feb 2026 10:22:05 +0800 Message-Id: <20260204022205.3204230-1-1468888505@139.com> 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: quoted-printable Content-Type: text/plain; charset="utf-8" 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:0x002000= 00 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> --- 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(-) diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_se= ssion.c index 5986d6d0a90b..e344475a41bd 100644 --- 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 ksmbd_session *se= ss, int id) int ksmbd_session_rpc_method(struct ksmbd_session *sess, int id) { struct ksmbd_session_rpc *entry; - int method; =20 - down_read(&sess->rpc_lock); + lockdep_assert_held(&sess->rpc_lock); entry =3D xa_load(&sess->rpc_handle_list, id); - method =3D entry ? entry->method : 0; - up_read(&sess->rpc_lock); =20 - return method; + return entry ? entry->method : 0; } =20 void ksmbd_session_destroy(struct ksmbd_session *sess) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index f4b3798279d9..eacfb241d3d4 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -4614,8 +4614,15 @@ static int smb2_get_info_file_pipe(struct ksmbd_sess= ion *sess, * pipe without opening it, checking error condition here */ id =3D 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); =20 ksmbd_debug(SMB, "FileInfoClass %u, FileId 0x%llx\n", req->FileInfoClass, req->VolatileFileId); diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c index a5b90d0b9f2d..53bfcf57f167 100644 --- a/fs/smb/server/transport_ipc.c +++ b/fs/smb/server/transport_ipc.c @@ -778,6 +778,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_write(struct ksmbd_= session *sess, int handle if (!msg) return NULL; =20 + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); msg->type =3D KSMBD_EVENT_RPC_REQUEST; req =3D (struct ksmbd_rpc_command *)msg->payload; req->handle =3D handle; @@ -786,6 +789,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_write(struct ksmbd_= session *sess, int handle req->flags |=3D KSMBD_RPC_WRITE_METHOD; req->payload_sz =3D payload_sz; memcpy(req->payload, payload, payload_sz); + up_read(&sess->rpc_lock); =20 resp =3D ipc_msg_send_request(msg, req->handle); ipc_msg_free(msg); @@ -802,6 +806,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_read(struct ksmbd_s= ession *sess, int handle) if (!msg) return NULL; =20 + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); msg->type =3D KSMBD_EVENT_RPC_REQUEST; req =3D (struct ksmbd_rpc_command *)msg->payload; req->handle =3D handle; @@ -809,6 +816,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_read(struct ksmbd_s= ession *sess, int handle) req->flags |=3D rpc_context_flags(sess); req->flags |=3D KSMBD_RPC_READ_METHOD; req->payload_sz =3D 0; + up_read(&sess->rpc_lock); =20 resp =3D ipc_msg_send_request(msg, req->handle); ipc_msg_free(msg); @@ -829,6 +837,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioctl(struct ksmbd_= session *sess, int handle if (!msg) return NULL; =20 + lockdep_assert_not_held(&sess->rpc_lock); + + down_read(&sess->rpc_lock); msg->type =3D KSMBD_EVENT_RPC_REQUEST; req =3D (struct ksmbd_rpc_command *)msg->payload; req->handle =3D handle; @@ -837,6 +848,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioctl(struct ksmbd_= session *sess, int handle req->flags |=3D KSMBD_RPC_IOCTL_METHOD; req->payload_sz =3D payload_sz; memcpy(req->payload, payload, payload_sz); + up_read(&sess->rpc_lock); =20 resp =3D ipc_msg_send_request(msg, req->handle); ipc_msg_free(msg); --=20 2.34.1