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=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A4066C432C2 for ; Thu, 26 Sep 2019 05:58:05 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id C432B222C5 for ; Thu, 26 Sep 2019 05:58:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XoAnc0BE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C432B222C5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16939-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 26315 invoked by uid 550); 26 Sep 2019 05:57:57 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 1024 invoked from network); 25 Sep 2019 20:17:22 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc :content-transfer-encoding; bh=J/s5UzAqezbutC2oi9AdlFVsV79wc1mf153fqreYkJA=; b=XoAnc0BEr4KHsLAuzeHQBerOL8lPo77zoG87AKkcm6jIrLTJwywECfIyo5boErAtWS 91dT7Bw6TTfD0lTbD33dFgUVtjxVhH926ISFxggsUo1OMZ70Cyrpe5sKtIHLzl3OIVpI hQ2wWjw1EwzlbPlyaHbAnNh4CvOHpTzDO7rsOtFTESAnFWgNa++TKlX3n2RCYZgopNi0 PcMXjeRWKJPVng8GjExZOfTfXW3fDbwTp2orQmx3sEbFxH8ALeEnFP7HatVCuEVggdam o5/aYPurmcLgVIFaEH1L/PbC3vyU8B0UpEfmfjV24fn5a4/uVGcq7ULN3wps313OTUGk SADg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc :content-transfer-encoding; bh=J/s5UzAqezbutC2oi9AdlFVsV79wc1mf153fqreYkJA=; b=KGFcvaUEQ0wELWSWxNZ4eUPKACwsMgBCq/V88Zi+bEk5Xk7Yz+iG5fNmkr97xShP2R ni8919dJ8MYpDKJOmHbWkbgj0OQATwg1rySnEpQSf8jM+6TuO+esg5zEAadS27q+4kg7 tHdjE41rMHM0BmPL8iKYsqHL9X0dLyudFVa1kYeDX2tuKMAJHRmoY3RyAZac6tnYSpVg k+JZzW7rFpy/WR28nVFJeYkBJ861ewNrncIHvJ3zu6gcdeEpULju7JQ3VHQrMD00GTnW nRunbq1TUfNs5LszfVOm4BFtjOhZCHqcQw2TjiMTgulII0FODc5BZVqvNnMD+/C81MRT ewLQ== X-Gm-Message-State: APjAAAUwLhcn6wjb1bFMuN7Lhn0rNXqZzZAlnnp707Lg6Y94YfyOHtsU R9qW6nCHvk/NwaCD4TaZH7iIj6TFWpOOBI8qVD9l/mHP X-Google-Smtp-Source: APXvYqyd+8rxxjJwXPgJRd0jPcCUyfx+W6Y+lSjoktiQDjrnhtDxLZG9EakMZjeaZ5WjHOCaYY5TPggbrX2H4Cjjc+Y= X-Received: by 2002:aca:39c1:: with SMTP id g184mr6134186oia.128.1569442630589; Wed, 25 Sep 2019 13:17:10 -0700 (PDT) MIME-Version: 1.0 From: Muni Sekhar Date: Thu, 26 Sep 2019 01:47:00 +0530 Message-ID: Subject: How to get the crash dump if system hangs? To: kernel-hardening@lists.openwall.com Cc: Kees Cook Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi All, I looked at the available tests with "cat /sys/kernel/debug/provoke-crash/DIRECT", from this I=E2=80=99d like to know which test causes system hang? I could not find any test case for deadlock, is any reason for this? I=E2=80=99m having a Linux system, I=E2=80=99m seeing it gets hung during c= ertain tests. When it hung, it does not even respond for SYSRQ button, only way to recover is power-button-only. Does no response for SYSRQ button means kernel crashed? After reboot I looked at the kern.log and most of the times it has =E2=80=9C^@^@^@^ ...=E2=80=9C line just before reboot. Can someone clarify = me what the kernel log entry =E2=80=9C^@^@^@^ ...=E2=80=9C means? I suspect kernel is c= rashed, but it does give any crashdump in kern.log. Later I enabled the kernel crash dump(sudo apt install linux-crashdump) and rerun the test but still nothing copied to the disk(/var/crash/). I don=E2=80=99t have onboard serial port in my machine, = so I tried get the crash dump via netconsole, but this method also does not able to catch the crash dump. Can someone help me how to debug in this scenario? And I'd like to know what other options available to get the crash dump? Can someone please clarify me on this? Also , does the crash dump fails if incase deadlock occurs? Any help will be greatly appreciated. --=20 Thanks, Sekhar