From patchwork Fri Dec 11 22:50:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Takashi Iwai X-Patchwork-Id: 342882 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=-16.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 785A1C433FE for ; Fri, 11 Dec 2020 22:52:56 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (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 A7A94206B7 for ; Fri, 11 Dec 2020 22:52:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7A94206B7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id E7F2B176D; Fri, 11 Dec 2020 23:52:03 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz E7F2B176D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1607727174; bh=h/gViz4biH66ZOf7E3+xdonpro9NW4DpmLv0PcmvmoY=; h=From:To:Subject:Date:In-Reply-To:References:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=nmAtE4XOt/ATJMRbFTsU3fxKfuxBhzEhUhkm+99XeOeYHXggS93tUje977AALu1P/ ByOL+G+5ZUFWWBk+toVhkNKbLpngFlwPbhXTMrWG0LcAix6yEzkYk5uHkuYrFYTiw9 nWSap/42b/yoIdp/4z5rxCun+2LTjXGa+f2+qo2Q= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 8563FF80240; Fri, 11 Dec 2020 23:51:13 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 56053F8021D; Fri, 11 Dec 2020 23:51:08 +0100 (CET) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id A1057F8011F for ; Fri, 11 Dec 2020 23:50:59 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz A1057F8011F X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B191DAC10; Fri, 11 Dec 2020 22:50:58 +0000 (UTC) From: Takashi Iwai To: alsa-devel@alsa-project.org Subject: [PATCH alsa-utils 2/2] alsactl: Fix race at creating a lock file Date: Fri, 11 Dec 2020 23:50:56 +0100 Message-Id: <20201211225056.12301-2-tiwai@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201211225056.12301-1-tiwai@suse.de> References: <20201211225056.12301-1-tiwai@suse.de> MIME-Version: 1.0 X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" A race at creating a lock file in state_lock() was discovered recently: namely, between the first open(O_RDWR) and the second open(O_RDWR|O_CREAT|O_EXCL) calls, another alsactl invocation may already create a lock file, then the second open() will return EEXIST, which isn't handled properly and treated as a fatal error. In this patch, we check EEXIST case and try again open() with O_RDWR. This must succeed usually, and if it fails, handle finally as the fatal error. BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1179904 Signed-off-by: Takashi Iwai --- alsactl/lock.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/alsactl/lock.c b/alsactl/lock.c index 05f6e4d2a102..5b4746231996 100644 --- a/alsactl/lock.c +++ b/alsactl/lock.c @@ -63,10 +63,15 @@ static int state_lock_(const char *file, int lock, int timeout, int _fd) if (fd < 0) { if (errno == EBUSY || errno == EAGAIN) { sleep(1); - } else { - err = -errno; - goto out; + continue; } + if (errno == EEXIST) { + fd = open(nfile, O_RDWR); + if (fd >= 0) + break; + } + err = -errno; + goto out; } } }