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=1793735274; b=zqAowaQhoPX+I+ABZGxqDqh3As+yi+jM0bMlWr14s4V0mq0NBrKUhWxP0wiqJ8nPrIGs 9L4AaW5qUmy3QHG8XYw2UpHciWfyLIWgSZKqQjluUx7fNDINn9ngd8OFdCnUg4YiYTgvh H8AqflaobS9hjiHrcYj8Ktxr1BQpTBbtBW3XCx8GSEci3uXbfTuxMjEeUmW5nTB/8rG6h kVatol7RBpqqKKUyWgiFurdbFZDtmXqxMzbo0LDLuvMH2SKCS9kC9uAYGBydQLiq0OJwD iXJd5q6bS84fAIbCIdh9XKxdjZ6v/v7FmmRBZ2IhhYgpZTK9u0L3/6botYNFjKa4eog== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793735274; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=RFDP1+qeI/6PE5pzKeEg2jAo+1vbuaZZQsZqEYbMZig=; b=diEvJLLWgUSG7+2ryTXmiBfYBACe/NDMyPy8lTdbfaUtLV9N5CHS4BZfFDxsl9cm4Xgy 6Yw0NRV5RUmNJ34MuW564DkOuvtFg84Y6eFYPbVqtJJ2k1NfInZlk3aFqsSZeiavMAWmc gV6KS2eD0l8ZW9R6gCtoBuKe0QDfeiBB7pCfBxJqibmDO3/Z405oESRxQRiagmBLV5NBc L9fIqS/gaumSH+RIJporkBNBYPIV7CltfBPdBYFfCxcC9zz3vpxAgLO561S1fibefOKdS DpIHR26oWWnIKhxFj3LvRmjtaJx9movm+ReEmP74Te0uuqN0vhHTWcF/CIGLJLo/GQQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=f4OiUkxb; 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 0ADA0606D811 for ; Tue, 3 Nov 2026 19:47:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=f4OiUkxb Received: by smtp.kernel.org (Postfix) with ESMTPSA id 432661F00A02; Tue, 3 Nov 2026 19:47:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793735273; bh=RFDP1+qeI/6PE5pzKeEg2jAo+1vbuaZZQsZqEYbMZig=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=f4OiUkxbUNC+mZwD3QR0QnlPwFSYAtsy+XoPt9aUkXWQ7p1QwklOWJ8t31UklnzVr 71xhAMCMhrBvV5NGJ4AGLgXWs+KqOJfqLuoAz1R0puTSxqWJdUBg+RyV7nzqBHM3pe GYDFRcBSTHq5Uw8ID/qJkYHIwpJZeQYDMov6Rb0R4iFiU1YtOiov2p0knTeKmmD4Z8 VddG1YWPIQ2sNbV51pVY3XWBUV7K1TmG0FesvlkYGd9FjOrVVDcBdlHSYeOzILtu71 ld3ExivYBvO4K/n05QHEfgpIBkScPV6yzuPp0duhuXBDt6KBrC+SlXdSg4T7RFk4HP jdc0qoSZxaV+A== From: Sasha Levin To: stable@vger.kernel.org Cc: Namjae Jeon , zdi-disclosures@trendmicro.com, Sasha Levin Subject: [PATCH 6.6.y] ksmbd: prevent stale data from being written by SMB2 WRITE requests Date: Tue, 3 Nov 2026 14:47:51 -0500 Message-ID: <20261103170316.642979-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110351-marsupial-sandbar-d3cd@gregkh> References: <2026110351-marsupial-sandbar-d3cd@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-Transfer-Encoding: 8bit From: Namjae Jeon [ Upstream commit bc0e0f5ac1d7b044d403f859406b4b66d4b1ce9b ] 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 [ sashal: replaced smb2_current_req_len() calls with inline NextCommand and RFC1002 length calculations ] Signed-off-by: Sasha Levin --- fs/smb/server/connection.c | 1 + fs/smb/server/smb2pdu.c | 34 +++++++++++++++++++++++++--------- 2 files changed, 26 insertions(+), 9 deletions(-) diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c index ec265f12c4902..833105f23d260 100644 --- a/fs/smb/server/connection.c +++ b/fs/smb/server/connection.c @@ -520,6 +520,7 @@ 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 aaccef2e3f3bb..d8aa61602b827 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -7140,23 +7140,28 @@ 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 = le32_to_cpu(req->hdr.NextCommand); + if (!req_len) + req_len = get_rfc1002_len(work->request_buf) - + work->next_smb2_rcv_hdr_off; - 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) { @@ -7307,14 +7312,25 @@ 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 = le32_to_cpu(req->hdr.NextCommand); + + if (!req_len) + req_len = get_rfc1002_len(work->request_buf) - + work->next_smb2_rcv_hdr_off; + + 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); -- 2.53.0