From patchwork Fri Feb 26 18:26:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 12107079 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 A34C1C433E0 for ; Fri, 26 Feb 2021 18:27:27 +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 29A0D64F1F for ; Fri, 26 Feb 2021 18:27:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29A0D64F1F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.90553.171462 (Exim 4.92) (envelope-from ) id 1lFhpN-0005FH-IQ; Fri, 26 Feb 2021 18:27:01 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 90553.171462; Fri, 26 Feb 2021 18:27:01 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lFhpN-0005FA-FM; Fri, 26 Feb 2021 18:27:01 +0000 Received: by outflank-mailman (input) for mailman id 90553; Fri, 26 Feb 2021 18:27:00 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lFhpM-0005F5-4s for xen-devel@lists.xenproject.org; Fri, 26 Feb 2021 18:27:00 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lFhpK-0001GE-TR; Fri, 26 Feb 2021 18:26:58 +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 1lFhpK-00089O-G4; Fri, 26 Feb 2021 18:26:58 +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=iNuTvkc4LGs0VPE3lG554tVwPfj5Ug5Vg9CmENqGtyQ=; b=hMRJuUFgprHCGy+sCM2Y8Xqu4P 7eMu2yWG4Z2lOPbCotS9SYYOcT3936s+7ChDl4mRUlLBOkiImdiDX8KL9toL+8Sqab5TYXzEbkFD9 2KH1g2hRlSGKfFyfIeuEpkRAYitNcolXn/UeXX+aYI8Eps26/g52CDQlP+rKTN1cpMsw=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: raphning@amazon.co.uk, iwj@xenproject.org, Julien Grall , Wei Liu , Juergen Gross Subject: [PATCH for-4.15] tools/xenstored: Avoid dereferencing a NULL pointer if LiveUpdate is failing Date: Fri, 26 Feb 2021 18:26:55 +0000 Message-Id: <20210226182655.2499-1-julien@xen.org> X-Mailer: git-send-email 2.17.1 From: Julien Grall In case of failure in do_lu_start(), XenStored will first free lu_start and then try to dereference it. This will result to a NULL dereference as the destruction callback will set lu_start to NULL. The crash can be avoided by freeing lu_start *after* the reply has been set. Fixes: af216a99fb4a ("tools/xenstore: add the basic framework for doing the live update") Signed-off-by: Julien Grall Reviewed-by: Juergen Gross --- This is a bug fix candidate for 4.15. The easiest way to trigger it is to have a XTF test that starts a transaction but never terminates it. In this case, live-updating would fail and trigger a crash. --- tools/xenstore/xenstored_control.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/tools/xenstore/xenstored_control.c b/tools/xenstore/xenstored_control.c index 653890f2d9e0..766b2438396a 100644 --- a/tools/xenstore/xenstored_control.c +++ b/tools/xenstore/xenstored_control.c @@ -657,9 +657,8 @@ static bool do_lu_start(struct delayed_request *req) /* We will reach this point only in case of failure. */ out: - talloc_free(lu_status); - send_reply(lu_status->conn, XS_CONTROL, ret, strlen(ret) + 1); + talloc_free(lu_status); return true; }