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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 99D85C47080 for ; Tue, 1 Jun 2021 15:56:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D6BD61159 for ; Tue, 1 Jun 2021 15:56:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234177AbhFAP6e (ORCPT ); Tue, 1 Jun 2021 11:58:34 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:33236 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230288AbhFAP6d (ORCPT ); Tue, 1 Jun 2021 11:58:33 -0400 Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 332BB2194A; Tue, 1 Jun 2021 15:56:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1622563011; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type; bh=qGb5tB4jwloRRPIgnn3LUqNEbpCui0+cZLG2IFKN0no=; b=TgUDiSkv5XebmZ1R0mW+0NRAxHmjxH1KDh+V41PZ2MKukrmjL3Yjk8odHl3EREyYundquK zYSCY5MQseIrX537SOp0chNF735fVszxyL9ySxbLhZyXAcfkr1qPl4A3UeYyPdQrjKZ66J DoGJYnemDA6oytbMfwT/uTkZX+CUBbQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1622563011; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type; bh=qGb5tB4jwloRRPIgnn3LUqNEbpCui0+cZLG2IFKN0no=; b=7HLCIFfB1UWeckIg8LmK9U2ie9cOavrPWJNn+jkCDwyVRnVjOLN+6og0Wt+5d1C56Ys5dv C3kvQ79xRiw9jQAg== Received: from imap3-int (imap-alt.suse-dmz.suse.de [192.168.254.47]) by imap.suse.de (Postfix) with ESMTP id E44FF118DD; Tue, 1 Jun 2021 15:56:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1622563011; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type; bh=qGb5tB4jwloRRPIgnn3LUqNEbpCui0+cZLG2IFKN0no=; b=TgUDiSkv5XebmZ1R0mW+0NRAxHmjxH1KDh+V41PZ2MKukrmjL3Yjk8odHl3EREyYundquK zYSCY5MQseIrX537SOp0chNF735fVszxyL9ySxbLhZyXAcfkr1qPl4A3UeYyPdQrjKZ66J DoGJYnemDA6oytbMfwT/uTkZX+CUBbQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1622563011; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type; bh=qGb5tB4jwloRRPIgnn3LUqNEbpCui0+cZLG2IFKN0no=; b=7HLCIFfB1UWeckIg8LmK9U2ie9cOavrPWJNn+jkCDwyVRnVjOLN+6og0Wt+5d1C56Ys5dv C3kvQ79xRiw9jQAg== Received: from director2.suse.de ([192.168.254.72]) by imap3-int with ESMTPSA id /BYtNMJYtmCPYAAALh3uQQ (envelope-from ); Tue, 01 Jun 2021 15:56:50 +0000 Received: from localhost (brahms [local]) by brahms (OpenSMTPD) with ESMTPA id c074404b; Tue, 1 Jun 2021 15:56:50 +0000 (UTC) Date: Tue, 1 Jun 2021 16:56:50 +0100 From: Luis Henriques To: Peter Oberparleiter Cc: linux-kernel@vger.kernel.org Subject: gcov: NULL pointer dereference with gcc 9.3.1 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! Maybe this is a known (gcc?) issue, but I'm seeing a NULL pointer splat if I instrument my kernel (or a module, more specifically) using gcc 9.3.1. It looks like, during initialization in __gcov_init(), gcov_info struct is invalid: the filename seems to be correct but ->function is NULL and ->n_functions contains garbage. This will result in the NULL pointer if, for example, I run: # echo 1 > /sys/kernel/debug/gcov/reset Other installed gcc versions (7.5.0 and 10.3.0) work fine. Is this a know issue with this specific gcc versions? Anyway, it may be worth having something like (not tested!): diff --git a/kernel/gcov/gcc_base.c b/kernel/gcov/gcc_base.c index 3cf736b9f880..de3ea47f4f62 100644 --- a/kernel/gcov/gcc_base.c +++ b/kernel/gcov/gcc_base.c @@ -13,6 +13,11 @@ void __gcov_init(struct gcov_info *info) { static unsigned int gcov_version; + if (!info || !info->functions) { + pr_err_once("Invalid gcov_info structure\n"); + return; + } + mutex_lock(&gcov_lock); if (gcov_version == 0) { gcov_version = gcov_info_version(info); And also something similar in the clang code, I guess. I can send a real (tested) patch if you wish, but I just wanted to know if I'm missing something first. Cheers, -- Luis