From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793701137; b=LPBitKl6cFd7jBUStpWnS/UyP9/46RzJPgcQ1jOPzwVQKtbB0Jni/fZzRxVdy1vIp5tZ muEuJcc2DGH5ujE+PN/u6awlsOGEgedsLW3AB0dcz8Txvt5iOMcVqe2RRQ+pDXMO5Yglo B+oYdari77HS7JxpyU0ISg6VgfzdvXK8A3mUF+cvS+vUQKJHGiCob/JGNePgg7R8qNE8e RuMrHIbIuEZoFaEtYT1ZHj3he5YY0DLMm4MqLeMeA3VR68qKIUzYS3XQpxvrSlatFjECE Hnlv61jufks/djh+4zz+0+MLiM5/3RGrFqo6Motuhn9VaHM6AibHYlnJPjqH1cPNWwA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793701137; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=nombTKGiTM3Sd4+m/QVdPuwDI08TZZvQWhx6qPvzGpY=; b=idfJJa9r7urBXJ54kcYQDg1V4uYqMoLJ5HIvtHL6W5A0J7U22/zxU2exR4CzIh3eLIxA Zq1imwwhN50gGpeblgBI3ntbYsK7HYPfhHm2OPT0onqHmRJLx2+j8WaS2zbeqQivV08AR AxToIgfia6HSfd3rl2i2MEkf6Fs/FyC86ATKGhfHwY1mGnGzgJNUU6iFff+jy5zQTGYAP f1uuUoQhNPbaTSUjyO+HgIOwrXhxlADPhj4QaF++ZMSEn0YmA26LstjmpTNTxTWQ0WaUD ErJ+GHIsKeEUxSjj43sL9KXAQ32wlrmcFgwwa6rnEbYOJL0TxhhHCERMHQrlfzJCBOg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=hCcLNIUa; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7023E606A815 for ; Tue, 3 Nov 2026 10:18:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=hCcLNIUa Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8FC81F00919; Tue, 3 Nov 2026 10:18:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793701137; bh=nombTKGiTM3Sd4+m/QVdPuwDI08TZZvQWhx6qPvzGpY=; h=Subject:To:Cc:From:Date; b=hCcLNIUak+5GPRGLAPnEpXH/FQxobtOPuvTG3CkIONQWh3U2Km4ORRaQPbjuvXOyC yo2p1KfbV3GKhsnltGmR87u1lySFlMuukKQge+DDwa4ahhgIv9PzU9a/ciG8cChngA q5s1HldanJACO4jBrQlCMHTUd4yNCsysrsPDVoWc= Subject: FAILED: patch "[PATCH] ksmbd: prevent stale data from being written by SMB2 WRITE" failed to apply to 6.1-stable tree To: linkinjeon@kernel.org Cc: From: Date: Tue, 03 Nov 2026 11:18:52 +0100 Message-ID: <2026110352-entering-splice-bcab@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x bc0e0f5ac1d7b044d403f859406b4b66d4b1ce9b # git commit -s git send-email --to '' --in-reply-to '2026110352-entering-splice-bcab@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From bc0e0f5ac1d7b044d403f859406b4b66d4b1ce9b Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Mon, 7 Sep 2026 13:35:51 +0900 Subject: [PATCH] ksmbd: prevent stale data from being written by SMB2 WRITE requests Initialize the compatibility byte in request buffers without zeroing the entire allocation. Keep the one-byte compatibility exception for SMB2 messages so valid zero-length WRITE requests remain compatible, and validate the data range in the WRITE handlers against the current compound request before accessing it. This prevents stale request-buffer data from being written to files or sent to IPC pipes. Fixes: 443d61d1fa9f ("ksmbd: allocate one more byte for implied bcc[0]") Cc: stable@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-32436 Signed-off-by: Namjae Jeon diff --git a/fs/smb/server/compress.c b/fs/smb/server/compress.c index 5162fb84c755..3fcb3e44302e 100644 --- a/fs/smb/server/compress.c +++ b/fs/smb/server/compress.c @@ -65,6 +65,7 @@ static int __ksmbd_decompress_request(struct ksmbd_conn *conn, return -ENOMEM; *(__be32 *)out = cpu_to_be32(out_size); + out[out_size + 4] = 0; rc = smb_compression_decompress(conn->compress_algorithm, conn->compress_chained, conn->compress_pattern, diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c index d211861ff86f..3f8cc4998da5 100644 --- a/fs/smb/server/connection.c +++ b/fs/smb/server/connection.c @@ -752,6 +752,7 @@ int ksmbd_conn_handler_loop(void *p) if (!conn->request_buf) break; + conn->request_buf[pdu_size + 4] = 0; memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf)); /* diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 18602a4759c0..c792ed5ebbd3 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -9276,23 +9276,25 @@ static noinline int smb2_write_pipe(struct ksmbd_work *work) int err = 0, ret = 0; char *data_buf; size_t length; + unsigned int data_offset, req_len; WORK_BUFFERS(work, req, rsp); length = le32_to_cpu(req->Length); id = req->VolatileFileId; + data_offset = le16_to_cpu(req->DataOffset); + req_len = smb2_current_req_len(work, &req->hdr); - if ((u64)le16_to_cpu(req->DataOffset) + length > - get_rfc1002_len(work->request_buf)) { - pr_err("invalid write data offset %u, smb_len %u\n", - le16_to_cpu(req->DataOffset), - get_rfc1002_len(work->request_buf)); + if (data_offset < offsetof(struct smb2_write_req, Buffer) || + data_offset > req_len || length > req_len - data_offset) { + pr_err("invalid write data offset %u, length %zu, req_len %u\n", + data_offset, length, req_len); err = -EINVAL; goto out; } data_buf = (char *)(((char *)&req->hdr.ProtocolId) + - le16_to_cpu(req->DataOffset)); + data_offset); rpc_resp = ksmbd_rpc_write(work->sess, id, data_buf, length); if (rpc_resp) { @@ -9579,14 +9581,21 @@ int smb2_write(struct ksmbd_work *work) writethrough = true; if (is_rdma_channel == false) { - if (le16_to_cpu(req->DataOffset) < - offsetof(struct smb2_write_req, Buffer)) { + unsigned int data_offset = le16_to_cpu(req->DataOffset); + unsigned int req_len = smb2_current_req_len(work, &req->hdr); + + if (data_offset < offsetof(struct smb2_write_req, Buffer) || + data_offset > req_len || + length > req_len - data_offset) { + ksmbd_debug(SMB, + "invalid write data offset %u, length %zu, req_len %u\n", + data_offset, length, req_len); err = -EINVAL; goto out; } data_buf = (char *)(((char *)&req->hdr.ProtocolId) + - le16_to_cpu(req->DataOffset)); + data_offset); ksmbd_debug(SMB, "filename %pD, offset %lld, len %zu\n", fp->filp, offset, length);