From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FBD3C18E5B for ; Tue, 17 Mar 2020 00:45:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 11BC3205ED for ; Tue, 17 Mar 2020 00:45:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733135AbgCQApY (ORCPT ); Mon, 16 Mar 2020 20:45:24 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:53802 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733005AbgCQApX (ORCPT ); Mon, 16 Mar 2020 20:45:23 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id 47A2528AE2F From: Gabriel Krisman Bertazi To: jdike@addtoit.com Cc: richard@nod.at, anton.ivanov@cambridgegreys.com, linux-um@lists.infradead.org, linux-kernel@vger.kernel.org, Gabriel Krisman Bertazi , kernel@collabora.com, Martyn Welch Subject: [PATCH 1/2] um: ubd: Prevent buffer overrun on command completion Date: Mon, 16 Mar 2020 20:45:06 -0400 Message-Id: <20200317004507.1513370-2-krisman@collabora.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200317004507.1513370-1-krisman@collabora.com> References: <20200317004507.1513370-1-krisman@collabora.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On the hypervisor side, when completing commands and the pipe is full, we retry writing only the entries that failed, by offsetting io_req_buffer, but we don't reduce the number of bytes written, which can cause a buffer overrun of io_req_buffer, and write garbage to the pipe. Cc: Martyn Welch Signed-off-by: Gabriel Krisman Bertazi --- arch/um/drivers/ubd_kern.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c index 6627d7c30f37..0f5d0a699a49 100644 --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -1606,7 +1606,9 @@ int io_thread(void *arg) written = 0; do { - res = os_write_file(kernel_fd, ((char *) io_req_buffer) + written, n); + res = os_write_file(kernel_fd, + ((char *) io_req_buffer) + written, + n - written); if (res >= 0) { written += res; } -- 2.25.0