From patchwork Thu Sep 22 16:01:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Johannes Zink X-Patchwork-Id: 12985486 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C769C6FA82 for ; Thu, 22 Sep 2022 16:01:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229575AbiIVQBp (ORCPT ); Thu, 22 Sep 2022 12:01:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229499AbiIVQBo (ORCPT ); Thu, 22 Sep 2022 12:01:44 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F32E2B089D for ; Thu, 22 Sep 2022 09:01:42 -0700 (PDT) Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=irc.pengutronix.de) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1obOdx-0004PM-AU; Thu, 22 Sep 2022 18:01:41 +0200 Message-ID: <33059074b78110d4717efe09b887dd28ac77fe7f.camel@pengutronix.de> Subject: PROBLEM: Segfault in kconfig From: Johannes Zink To: masahiroy@kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org Cc: kernel@pengutronix.de Date: Thu, 22 Sep 2022 18:01:40 +0200 User-Agent: Evolution 3.38.3-1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:900:1d::77 X-SA-Exim-Mail-From: j.zink@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kbuild@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Hi everyone, [1.] One line summary of the problem: kconfig crashes with segfault under rare circumstances [2.] Full description of the problem/report: Under certain circumstances jump keys are displayed on the search  results even if a symbol is deactivated by one of its  dependencies. Using the jump keys then triggers a segmentation fault due to a NULL dereference. Perform the following steps to  trigger the issue 1.: ARCH=arm64 make defconfig 2.: ARCH=arm64 make menuconfig 3.: press '/' key to search for the string "EFI". Use jump key  (1) to jump to search result. Press 'n' key to deactivate the  entry.  4.: press '/' to seach for the string "ACPI". Use the jump key  (1) to jump to the search result.  Menuconfig then crashes with a segfault. [3.] Keywords (i.e., modules, networking, kernel): kconfig, mconf [4.] Kernel information [4.1.] Kernel version (from /proc/version): v6.0.0-rc6 [4.2.] Kernel .config file: arm64 default defconfig [5.] Most recent kernel version which did not have the bug: v5.15 [6.] Output of Oops.. message (if applicable) with symbolic information resolved (see Documentation/admin-guide/bug-hunting.rst): not applicable [7.] A small shell script or example program which triggers the problem (if possible): not applicable, please see description in [2.] [8.] Environment [8.1.] Software (add the output of the ver_linux script here): not applicable [8.2.] Processor information (from /proc/cpuinfo): not applicable [8.3.] Module information (from /proc/modules): not applicable [8.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem): not applicable [8.5.] PCI information ('lspci -vvv' as root): not applicable [8.6.] SCSI information (from /proc/scsi/scsi): not applicable [8.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant): not applicable [X.] Other notes, patches, fixes, workarounds: I found that the attached patch is a very hacky workaround to  keep menuconfig from crashing, but I am pretty sure the jump  keys should not have be activated for unaccessable entries in the first place. I found it quite hard to find the corresponding part in mconf, which is why I decided to send this bugreport instead  of sending a patch. Maybe someone on this list either knows mconf  really well and can just fix it, or guide me to where I can dig  around (though in that case I could really use some help on how  to debug menuconfig, since I found it challenging to get it  working with gdb) Best regards Johannes --- scripts/kconfig/mconf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) str_free(&res); diff --git a/scripts/kconfig/mconf.c b/scripts/kconfig/mconf.c index 9d3cf510562f..60a82f701bd3 100644 --- a/scripts/kconfig/mconf.c +++ b/scripts/kconfig/mconf.c @@ -447,7 +447,8 @@ static void search_conf(void) again = false; for (i = 0; i < JUMP_NB && keys[i]; i++) if (dres == keys[i]) { - conf(targets[i]->parent, targets[i]); + if (targets[i]->parent) + conf(targets[i]->parent, targets[i]); again = true; }