From patchwork Thu Jul 29 11:06:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 12408355 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 49957C4338F for ; Thu, 29 Jul 2021 11:07:05 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1315860EE6 for ; Thu, 29 Jul 2021 11:07:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1315860EE6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.161903.297094 (Exim 4.92) (envelope-from ) id 1m93sP-00029A-8P; Thu, 29 Jul 2021 11:06:57 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 161903.297094; Thu, 29 Jul 2021 11:06:57 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1m93sP-000293-54; Thu, 29 Jul 2021 11:06:57 +0000 Received: by outflank-mailman (input) for mailman id 161903; Thu, 29 Jul 2021 11:06:55 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1m93sN-00028t-Cu for xen-devel@lists.xenproject.org; Thu, 29 Jul 2021 11:06:55 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1m93sM-0004vm-OW; Thu, 29 Jul 2021 11:06:54 +0000 Received: from 54-240-197-235.amazon.com ([54.240.197.235] helo=ufe34d9ed68d054.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1m93sM-0006OX-FT; Thu, 29 Jul 2021 11:06:54 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Message-Id:Date:Subject:Cc:To:From; bh=9cjgZZnC+CjNZwAhAzGV3zUaO4AAHfmbwNPumDCV3o4=; b=j6Dgly8XOB/Pf8F23GKD7B3X/p XvW8vrQhnShAqewJk7w84qdrAzhBXXWIlA1h2fyHS+vssbDs1xGhYFt+CVebPBDXXLowa6ynrVAky KKlfMLWqv5p3xqfgxd8lS09A+kHsTS1ie03qDE1I9J2XMeJsLrUVQNqrU17PzvGvmhQU=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: julien@xen.org, Julien Grall , Ian Jackson , Wei Liu , Juergen Gross Subject: [PATCH] tools/xenstored: Don't assume errno will not be overwritten in lu_arch() Date: Thu, 29 Jul 2021 12:06:47 +0100 Message-Id: <20210729110647.25500-1-julien@xen.org> X-Mailer: git-send-email 2.17.1 From: Julien Grall At the moment, do_control_lu() will set errno to 0 before calling lu_arch() and then check errno. The expectation is nothing in lu_arch() will change the value unless there is an error. However, per errno(3), a function that succeeds is allowed to change errno. In fact, syslog() will overwrite errno if the logs are rotated at the time it is called. To prevent any further issue, errno is now always set before returning NULL. Additionally, errno is only checked when returning NULL so the client can see the error message if there is any. Reported-by: Michael Kurth Signed-off-by: Julien Grall Reviewed-by: Juergen Gross --- tools/xenstore/xenstored_control.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/tools/xenstore/xenstored_control.c b/tools/xenstore/xenstored_control.c index 6b68b79faac7..6fcb42095b59 100644 --- a/tools/xenstore/xenstored_control.c +++ b/tools/xenstore/xenstored_control.c @@ -324,6 +324,7 @@ static const char *lu_binary_alloc(const void *ctx, struct connection *conn, lu_status->kernel_size = size; lu_status->kernel_off = 0; + errno = 0; return NULL; } @@ -339,6 +340,7 @@ static const char *lu_binary_save(const void *ctx, struct connection *conn, memcpy(lu_status->kernel + lu_status->kernel_off, data, size); lu_status->kernel_off += size; + errno = 0; return NULL; } @@ -798,9 +800,8 @@ static int do_control_lu(void *ctx, struct connection *conn, if (!ret) return errno; } else { - errno = 0; ret = lu_arch(ctx, conn, vec, num); - if (errno) + if (!ret && errno) return errno; }