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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 2565FC433E0 for ; Tue, 19 Jan 2021 10:56:42 +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 C917E2075F for ; Tue, 19 Jan 2021 10:56:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C917E2075F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=armlinux.org.uk 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=cxOFBNOIvGSPHbdFVvMLQN/wshrsr4kkQV/EqpfConc=; b=QuGJIAIc9MlryxBTqGU0SB0EC ZT+Go3flf6gmv3jATmx+8awmj7RL1Kc/i23yEVD3RAeqFRdMNsVSlcuqHts6x/XrDTKpWIW6C8L8Y 3dCd4MguEF5Gd7cMo1lstro6+3JmTK64Tg8NU1ieO2/dChYGxemnsPdueov6QJbgSx+yx6BauoWAc XSoUyoEgKAzvTyWGdVlEUQNqB6RlmbY0Ehd16ewMJZVxDhjaYEfvCvLQVCrh3wXXPgJrV4P02p9Aa v+VCG56hQJYfvpvcdjgGP2r1+u9JB231Zjl4BH6sXlNTTYF/qPj6RvgvnAZQkLOSJM3UW86/hrVqy 5V6yNEzvg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l1ofW-0000Wj-8F; Tue, 19 Jan 2021 10:55:26 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l1ofU-0000WA-Ji for linux-arm-kernel@lists.infradead.org; Tue, 19 Jan 2021 10:55:25 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=yYjCJm0NaHXJ5lQO93HUKi5kDcNPXbb7+T3VlcBRWE4=; b=icziEYGDCg7IWdO2wbkuhp4UO LeyplOI9icBDCb1g3nrKy8wQCWImAqjfO76dgWT1nd1xc1pavXgkWtK/+a2y/PP6oZgxBRbpBxdHD fMYd6VMqOctTl//o+aiH4YwEOMu4cJiOvS5UKvYboQ2EzeYr+VccaDd58ubp7r2ZPGHXVoDGWyOZ4 VaXc4pTawRL3xFRC8khRT8crXw75kpAwv/DvHcTwGVGiv2M3cAHE3WRXNarDjNnKQN3di8xaIBtzB c/22h727X3c2WRGpzwnArBxYWUxOCMhl1a1BParKebL4mybtkLwxO0ftDprm9aeiS8ijIy6/6qyvU NPjEnIFoQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:49926) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1l1ofR-0007Gw-10; Tue, 19 Jan 2021 10:55:21 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1l1ofN-0004xC-Oq; Tue, 19 Jan 2021 10:55:17 +0000 Date: Tue, 19 Jan 2021 10:55:17 +0000 From: Russell King - ARM Linux admin To: Dmitry Vyukov Subject: Re: Arm + KASAN + syzbot Message-ID: <20210119105517.GG1551@shell.armlinux.org.uk> References: <20210119100355.GA21435@C02TD0UTHF1T.local> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210119_055524_655402_8C1C9D65 X-CRM114-Status: GOOD ( 11.67 ) 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: Mark Rutland , Arnd Bergmann , Linus Walleij , kasan-dev , syzkaller , Krzysztof Kozlowski , Hailong Liu , Linux ARM 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 Tue, Jan 19, 2021 at 11:34:33AM +0100, Dmitry Vyukov wrote: > My first guess would be is that current itself if NULL. Accesses to > current->kcov* are well tested on other arches, including using KCOV > in interrupts, etc. There is a window in dup_task_struct() where the new thread info has a NULL ->task pointer, but this will never be the current thread, and so would not affect current. If we do have a NULL current, that would cause the kernel to explode, since a context switch to or from such a case would dereference a NULL pointer. So, I think your theory is highly unlikely. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel