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=1793831956; b=tK63E25KkDNPQQKxkjP0xZNbinULynfbHx7E6UCabN/jsB9gBMV0HAma3QFkyIHxmTlX /rh5qz/shrD2NtXqxWds/usYieIOyjUmSt6nJXUhmXlNYwYmKcuGNE4w5Spawr8wAXPuM HpaB/mGmHSSqX1ezjZzGcHnPh/oxnGpLo1LQ064dI3BPlnvXQtGxXsPsx3hmnQnCgdEj6 7y4dE5KVm/PyfLD6/QMyH5JzspXFTT/xBXIpIW88Zgga5uRZcqdsbxnA3PWt8sK/YgdDY 1zSK7DowUGuY8MhtkWhoqCnvGACL9OMh83xCY4pKOKC6MPvsfs4gsmQSASL8WQErIDA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831956; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=w75BLrcYq/ahEGFc3yqJS8JFZU85jgJ3DK2SU43lTNE=; b=0ksFE62H9gTafY5La30MYGwsQ8eU4TzGZ6Zq2JjySnTxh35KE3sAV+u8jKLf1qNhyv30 yDeUG7MdjsVswBaI1HTND6sRbqAmKgZ2KxEFgZuuPVQXeqw/85l989ez8+3cFQtN1EYnm T1ymPK6YTwaisA6UQwAwV9pH4orgrrve1LYCb9OIHl9dcB6x22Xc/Mlf5gBxtunK0DRt5 VwAmhEXL3qpI1Stn6q4HOZeFktNm3ZCckFHYqOBpXZqCA2rzc1Ha9tGw+2muYLiOllFTS dKlBkA3533fcTksKlX76df6AMuEKIf6+TPvayzmIf3G3oJmnNoJmrjRQMvKLg7W+adQ== 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=B8GgUa25; 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 63B3C606A875; Wed, 4 Nov 2026 22:39:16 +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=B8GgUa25 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 003AD1F00919; Wed, 4 Nov 2026 22:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831956; bh=w75BLrcYq/ahEGFc3yqJS8JFZU85jgJ3DK2SU43lTNE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=B8GgUa25IIsrIUMDs0nyuhnBLN59Qy57huef2f2ht0wDNfgKEGqYMLg9FZP5VY7HG eoxI8CzG0m79qVSUJxOf+SQFreG8BtJx0xTqoXDg12OsgWsi0JbcFJJr+Z34lYjf2B /3E9vsoOW/UpD6W5pdZSHQ/n1++Ls0B/LbzwY8l4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Namjae Jeon , Sasha Levin , zdi-disclosures@trendmicro.com Subject: [PATCH 6.18 0989/1005] ksmbd: prevent stale data from being written by SMB2 WRITE requests Date: Wed, 4 Nov 2026 16:12:02 -0500 Message-ID: <20261104211110.740515746@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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: Inlined the unavailable smb2_current_req_len() helper and omitted the decompression change because compression support is absent. ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/connection.c | 1 + fs/smb/server/smb2pdu.c | 36 ++++++++++++++++++++++++++---------- 2 files changed, 27 insertions(+), 10 deletions(-) --- a/fs/smb/server/connection.c +++ b/fs/smb/server/connection.c @@ -520,6 +520,7 @@ recheck: if (!conn->request_buf) break; + conn->request_buf[pdu_size + 4] = 0; memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf)); /* --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -7218,23 +7218,28 @@ static noinline int smb2_write_pipe(stru 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; - - 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)); + 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 (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) { @@ -7391,14 +7396,25 @@ 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);