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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 68060C2D0BF for ; Mon, 16 Dec 2019 17:37:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3DE26206EC for ; Mon, 16 Dec 2019 17:37:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="amZwGNh+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726141AbfLPRho (ORCPT ); Mon, 16 Dec 2019 12:37:44 -0500 Received: from mail.skyhub.de ([5.9.137.197]:50146 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbfLPRhn (ORCPT ); Mon, 16 Dec 2019 12:37:43 -0500 Received: from zn.tnic (p200300EC2F07BC00D0F2C92C76B3ABC9.dip0.t-ipconnect.de [IPv6:2003:ec:2f07:bc00:d0f2:c92c:76b3:abc9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id A405E1EC090E; Mon, 16 Dec 2019 18:37:42 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1576517862; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZIuQ4SBAYWTtmbd3i6y0A5cJd1GBpHw6PKo/pLo8a+4=; b=amZwGNh+x4wmCQD4hTMj7OhEe+SJh5f6ndvlCenqLGvcFKpR5mnpoJTtx6gHImXqhGceMR cS+Ll8bzg52kI7NC+nJQvdznmfq5VVDsi7R2Bcw5yI7+XuKWHBH9v6XltGHavvw1oZLChv gJesnWHvhRyeT6uevuc+GI1w9B/2RIU= Date: Mon, 16 Dec 2019 18:37:37 +0100 From: Borislav Petkov To: Jan =?utf-8?Q?H=2E_Sch=C3=B6nherr?= Cc: Tony Luck , linux-edac@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Subject: Re: [PATCH 4/6] x86/mce: Fix handling of optional message string Message-ID: <20191216173737.GF17380@zn.tnic> References: <20191210000733.17979-1-jschoenh@amazon.de> <20191210000733.17979-5-jschoenh@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191210000733.17979-5-jschoenh@amazon.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-edac-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org On Tue, Dec 10, 2019 at 01:07:31AM +0100, Jan H. Schönherr wrote: > The function mce_severity() is not required to update its msg argument. > In fact, mce_severity_amd() doesn't. Fix some code paths, that assume > that it is always updated. > > In particular, this avoids returning uninitialized data in > mce_no_way_out(), which may be used later for printing. > > Signed-off-by: Jan H. Schönherr > --- > arch/x86/kernel/cpu/mce/core.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 6afb9de251f2..b11a74e3fea9 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -809,10 +809,12 @@ static int mce_no_way_out(struct mce *m, char **msg, unsigned long *validp, > if (quirk_no_way_out) > quirk_no_way_out(i, m, regs); > > + tmp = NULL; > m->bank = i; > if (mce_severity(m, mca_cfg.tolerant, &tmp, true) >= MCE_PANIC_SEVERITY) { > mce_read_aux(m, i); > - *msg = tmp; > + if (tmp) > + *msg = tmp; > return 1; > } > } > @@ -1313,6 +1315,7 @@ void do_machine_check(struct pt_regs *regs, long error_code) > * make sure we have the right "msg". > */ > if (worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) { > + msg = "Unknown"; > mce_severity(&m, cfg->tolerant, &msg, true); > mce_panic("Local fatal machine check!", &m, msg); > } > -- Can we get rid of all that silliness of dealing with a possibly uninitialized pointer in the callers and simply do at the beginning of mce_panic(): if (!msg) msg = "Unknown"; ? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette