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=1794061823; b=Rn9XoXMkqc0rPQ37/Tr82ewH4QpO6Pq2T+VnFUE6SwiJBPs3Pc/cW6UwtKYlyon3jrWg /6Bp2Q+/SKU4pdaXrce+u+pkHKeX7tlzdCFfTOcWxAv5kSFqvhHGZqUhcOcyq0XZDtrWh nLrltUMosjJEM42elj0ShcllWil14Vvkex/AlajwvYRFihEQAueLKbdgryMMJtVppSf9J //KaUo6Ejg6OoD2hwBNqnAEJkijIr3bQhg/rbFTztSiQFvPbTxK5T3vRtHd+YyY0RJDCB lIyDWw+glZWDEfw+kx++gwDoauMifG5UKBMhDxc0HFmJCTLR5vvQhivmXJbM9ehr0HQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061823; 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=jmaQNd/HuFUbsQEuw8Fd8gI7KeXE8WYw1K1DHkEMbLk=; b=hTVaKHCQAWqJoA78AOtsKy8zEJCkiEOCuBMOmijN5wOTarn3ioWpia2ni4SJ5zM1h37c 7d2Z/wlPXFmuUZOW4WHnDFihzKuZYxklaGUzDJulzllSSQRHaFO6y0Cbt0W4hw6JLS42s NzAMYTJyLGxsviKIWLhhRrfEbcSm3aUquOyk3qAJ1lTPgoBnlGzKE8+J8LG0mvlOi+P9D 9oXoiaHl0t/a8O6G6Tga0zc9yx6z7TqUx6fZIiPcE+37WbKUhSoTjlQobfClphfh3CdrN 8hGy+kFHjsH7WmI1B0IrKhtvedy5J28oOVvtIDZUrTkJJjCVHLYgJCy6NAfLgdmp/QQ== 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=m6xm6shU; 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 4B414606A326; Sat, 7 Nov 2026 14:30:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=m6xm6shU Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECB311F0089F; Sat, 7 Nov 2026 14:30:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061823; bh=jmaQNd/HuFUbsQEuw8Fd8gI7KeXE8WYw1K1DHkEMbLk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=m6xm6shUyK6XVERm5bx1KAso6FUrHAf6BPimT7iQ5wnp+gkTkFABUhD8iZCX+aX+a y/BC5oNOS6JsRVv2DYrBqS7zO6Dalsd1WrJ8tn2BZbLUMC3Idbus8qukX+/SzpE5mz YPYtKThK+yw0Qs/D4hIo+kmT5W5TXgmd+bHmkKv4= 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 6.12 0846/1536] ksmbd: prevent stale data from being written by SMB2 WRITE requests Date: Sat, 7 Nov 2026 08:47:42 -0500 Message-ID: <20261107135021.310170992@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.12-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: replaced smb2_current_req_len() calls with inline request-length calculations using NextCommand and the receive-buffer offset ] 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 d3dd89e612c6e..b532e553301aa 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 b56de54564664..9d9540ca97bc8 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -7173,23 +7173,28 @@ 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) { @@ -7340,14 +7345,25 @@ 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