Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752156AbdIKQgE (ORCPT ); Mon, 11 Sep 2017 12:36:04 -0400 Received: from mail-yw0-f176.google.com ([209.85.161.176]:32850 "EHLO mail-yw0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751894AbdIKQgC (ORCPT ); Mon, 11 Sep 2017 12:36:02 -0400 X-Google-Smtp-Source: ADKCNb6y+7KzeOMPKjUSXijfDFY2aMp1PkrTSbmvSwK9czrHAXnnky5kxyNYRCGL6DUljHOwcq8tRpZClO/7vvFW+xE= MIME-Version: 1.0 In-Reply-To: <20170910035815.GA9834@roeck-us.net> References: <20170910035815.GA9834@roeck-us.net> From: Kees Cook Date: Mon, 11 Sep 2017 09:36:00 -0700 X-Google-Sender-Auth: irqUYyX1yoB_-JDDR-8l6cAek48 Message-ID: Subject: Re: nios2 crash due to 'init/main.c: extract early boot entropy from the passed cmdline' To: Guenter Roeck Cc: Daniel Micay , LKML , Ley Foon Tan , nios2-dev@lists.rocketboards.org, Laura Abbott , Andrew Morton Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3016 Lines: 53 On Sat, Sep 9, 2017 at 8:58 PM, Guenter Roeck wrote: > Hi, > > I noticed that nios2 images crash in mainline. Bisect points to commit > 33d72f3822d7 ("init/main.c: extract early boot entropy from the passed > cmdline"). Bisect log is attached. > > As far as I can see, the problem is seen because add_device_randomness() > calls random_get_entropy(). However, the underlying timer function > used by the nios2 architecture (nios2_timer_read) is not yet initialized, > causing a NULL pointer access and crash. A sample crash log is at > http://kerneltests.org/builders/qemu-nios2-master/builds/175/steps/qemubuildcommand/logs/stdio Oh, yikes. Do you have a full call trace? (Does this come through get_cycles() or via the It seems like we could either initialize the timer earlier or allow it to fall back when not initialized... -Kees > > Guenter > > --- > # bad: [4dfc2788033d30dfccfd4268e06dd73ce2c654ed] Merge tag 'iommu-updates-v4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu > # good: [5969d1bb3082b41eba8fd2c826559abe38ccb6df] Merge branch 'gperf-removal' > git bisect start 'HEAD' '5969d1bb3082' > # bad: [fbd01410e89a66f346ba1b3c0161e1198449b746] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net > git bisect bad fbd01410e89a66f346ba1b3c0161e1198449b746 > # good: [0d519f2d1ed1f11e49abc88cfcf6cf13b83ba14c] Merge tag 'pci-v4.14-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci > git bisect good 0d519f2d1ed1f11e49abc88cfcf6cf13b83ba14c > # bad: [229cf16d3c8ac2e9b082c223fd0e619dc8f62cc1] sh: defconfig: cleanup from old Kconfig options > git bisect bad 229cf16d3c8ac2e9b082c223fd0e619dc8f62cc1 > # good: [1caffba9db4aa27c3e7ebc05668afca1f991ab8d] drivers/scsi/sym53c8xx_2/sym_hipd.c: convert to use memset32 > git bisect good 1caffba9db4aa27c3e7ebc05668afca1f991ab8d > # good: [7c61bd6983b185272315722787cceacf5f5d2e7d] lib/cmdline.c: remove meaningless comment > git bisect good 7c61bd6983b185272315722787cceacf5f5d2e7d > # bad: [718b303b49893d8f9dd469f710d76f77673bd35d] autofs: use AUTOFS_DEV_IOCTL_SIZE > git bisect bad 718b303b49893d8f9dd469f710d76f77673bd35d > # good: [9367bb730e4d9d85a8911a08a3542ec2aa873d37] binfmt_flat: delete two error messages for a failed memory allocation in decompress_exec() > git bisect good 9367bb730e4d9d85a8911a08a3542ec2aa873d37 > # bad: [e54c7bcbf14a25dc3a913b4c808b52121c522e9b] autofs: make disc device user accessible > git bisect bad e54c7bcbf14a25dc3a913b4c808b52121c522e9b > # bad: [33d72f3822d7ff8a9e45bd7413c811085cb87aa5] init/main.c: extract early boot entropy from the passed cmdline > git bisect bad 33d72f3822d7ff8a9e45bd7413c811085cb87aa5 > # good: [121388a31362b0d3176dc1190ac8064b98a61b20] init: move stack canary initialization after setup_arch > git bisect good 121388a31362b0d3176dc1190ac8064b98a61b20 > # first bad commit: [33d72f3822d7ff8a9e45bd7413c811085cb87aa5] init/main.c: extract early boot entropy from the passed cmdline -- Kees Cook Pixel Security