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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 AD124C00A89 for ; Thu, 5 Nov 2020 10:53:21 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 46015206FA for ; Thu, 5 Nov 2020 10:53:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="nFqUpovQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46015206FA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=SToISaN4RETjI3s/7GMbxcqYPfouc0wdV+N7BwdIcsQ=; b=nFqUpovQWutz0rUbCKS74WCnO NWjkHGHS0SebLOmm2rjMH8o4Zb/ecOFo5G4qgg8HEsaQtGy7Xa3SBv8Ca80rR21H6lfoMuGRmUArm lDjq+Ah7ty25L9BNHr46l7eFHrHr2GsPvBiJhuukSHbLPXsSdh2jvoEx0ivQRH0fckt+4E+5pXOYs 0AhAF34mEnANbIehzMcRIL9n4Cl3foxBwf24J6r7vSX7WzYWw5oXUU3rEsNASZmo01I8wXXz0lTSk VufbFcjvcsVbGZsKc1VyM0jCT0ICgbHmbsd4uZQ1rFOd7rqtMWP5UnUAuHClZTjjO8ttAxQEJAKg5 a+55yeO8A==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kacsv-0004R1-7A; Thu, 05 Nov 2020 10:52:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kacss-0004Pp-Sx for linux-arm-kernel@lists.infradead.org; Thu, 05 Nov 2020 10:52:51 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 63BAE142F; Thu, 5 Nov 2020 02:52:46 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.58.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 848743F66E; Thu, 5 Nov 2020 02:52:44 -0800 (PST) Date: Thu, 5 Nov 2020 10:52:41 +0000 From: Mark Rutland To: Marco Elver Subject: Re: [PATCH] kfence: Use pt_regs to generate stack trace on faults Message-ID: <20201105105241.GC82102@C02TD0UTHF1T.local> References: <20201105092133.2075331-1-elver@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201105092133.2075331-1-elver@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201105_055250_991969_989DC64F X-CRM114-Status: GOOD ( 20.93 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jannh@google.com, x86@kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, glider@google.com, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, dvyukov@google.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 05, 2020 at 10:21:33AM +0100, Marco Elver wrote: > Instead of removing the fault handling portion of the stack trace based > on the fault handler's name, just use struct pt_regs directly. > > Change kfence_handle_page_fault() to take a struct pt_regs, and plumb it > through to kfence_report_error() for out-of-bounds, use-after-free, or > invalid access errors, where pt_regs is used to generate the stack > trace. > > If the kernel is a DEBUG_KERNEL, also show registers for more > information. > > Suggested-by: Mark Rutland > Signed-off-by: Marco Elver Wow; I wasn't expecting this to be put together so quickly, thanks for doing this! >From a scan, this looks good to me -- just one question below. > diff --git a/include/linux/kfence.h b/include/linux/kfence.h > index ed2d48acdafe..98a97f9d43cd 100644 > --- a/include/linux/kfence.h > +++ b/include/linux/kfence.h > @@ -171,6 +171,7 @@ static __always_inline __must_check bool kfence_free(void *addr) > /** > * kfence_handle_page_fault() - perform page fault handling for KFENCE pages > * @addr: faulting address > + * @regs: current struct pt_regs (can be NULL, but shows full stack trace) > * > * Return: > * * false - address outside KFENCE pool, > @@ -44,8 +44,12 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries > case KFENCE_ERROR_UAF: > case KFENCE_ERROR_OOB: > case KFENCE_ERROR_INVALID: > - is_access_fault = true; > - break; > + /* > + * kfence_handle_page_fault() may be called with pt_regs > + * set to NULL; in that case we'll simply show the full > + * stack trace. > + */ > + return 0; For both the above comments, when/where is kfence_handle_page_fault() called with regs set to NULL? I couldn't spot that in this patch, so unless I mised it I'm guessing that's somewhere outside of the patch context? If this is a case we don't expect to happen, maybe add a WARN_ON_ONCE()? Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel