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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2524C433F5 for ; Wed, 16 Mar 2022 13:23:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240257AbiCPNZG (ORCPT ); Wed, 16 Mar 2022 09:25:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241443AbiCPNZF (ORCPT ); Wed, 16 Mar 2022 09:25:05 -0400 Received: from wout1-smtp.messagingengine.com (wout1-smtp.messagingengine.com [64.147.123.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12B8D33E37; Wed, 16 Mar 2022 06:23:52 -0700 (PDT) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 49B613202010; Wed, 16 Mar 2022 09:23:51 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute2.internal (MEProxy); Wed, 16 Mar 2022 09:23:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kkourt.io; h=cc :cc:content-transfer-encoding:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=mesmtp; bh=bENHhIi915KsPjgABUpRtuQfqeP QoymgG+Vo887wrCc=; b=ThPMiqaRipdQRREPicRBAfL5RZN0Arp5CRNwQRMghW7 IWz9jCKtOtIPwN8ER78Y66h6G6DnWYO6Vgh6+uQQf2A4aCYckDwBJSg2Ypi58Ono GAxxHyXJ5SmCAjmWMtaQufccAPWVZArFiePoH1oHzVNPKRtUR9oR8JTxko8GIS8Q = DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding:date:date :from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:sender:subject:subject:to:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=bENHhI i915KsPjgABUpRtuQfqePQoymgG+Vo887wrCc=; b=GVZ8IFqGGnEylI1Gd/HqP1 BfIk46n62ljKMPRmki2auOerraMtzlXsbxc4dZa0QlbMEsi9b8nAR++hkFbEusys iAS7QayhoYvUtlstxONb2pF87IfH46xrXAgivb8d18f3Fn+DEInCdwi53Q1we6bW 6YONofyrAvqBwD+by6PFo7guABjStb22r23a/fz2UgPuzN1i+JF6FAucjErcR/sH E+P2Atu1XxOAe3yff8zkSn9Px6JQcKG2TBQvhjNMRiLKjpH64BsJZ+MvY69JZFil JQVI7nykMKDhajiabYjZsDCd+iNLVSgnYaIVQNm3KWilkdQ98i5mLWTTBwvNbSrg == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddrudefvddggeelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufffkffojghfggfgsedtkeertdertddtnecuhfhrohhmpehkkhhouhhr theskhhkohhurhhtrdhiohenucggtffrrghtthgvrhhnpeekkeeuiedujeekvdefjefffe eggfdugeettdeiieevgffghfelgeetffeijeegffenucffohhmrghinhepshhouhhrtggv figrrhgvrdhorhhgnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilh hfrhhomhepkhhkohhurhhtsehkkhhouhhrthdrihho X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 16 Mar 2022 09:23:50 -0400 (EDT) Received: by kkourt.io (Postfix, from userid 1000) id 21ADB2541B5C; Wed, 16 Mar 2022 14:23:48 +0100 (CET) From: kkourt@kkourt.io To: Arnaldo Carvalho de Melo Cc: dwarves@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Kornilios Kourtis Subject: [PATCH 1/2] pahole: avoid segfault when parsing bogus file Date: Wed, 16 Mar 2022 14:23:38 +0100 Message-Id: <20220316132338.3226871-1-kkourt@kkourt.io> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org From: Kornilios Kourtis When trying to use btf encoding for an apparently problematic kernel file, pahole segfaults. As can be seen below [1], the problem is that we are trying to dereference a NULL decoder. Fix this by checking the return value of dwfl_getmodules which [2] whill return -1 on errors or an offset if one of the modules did not return DWARF_CB_OK. (In this specific case, it was __cus__load_debug_types that returned DWARF_CB_ABORT.) [1]: $ gdb -q --args ./pahole -J vmlinux-5.3.18-24.102-default.debug Reading symbols from ./pahole... (gdb) r Starting program: /tmp/pahole/build/pahole -J vmlinux-5.3.18-24.102-default.debug [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7f4000e in gobuffer__size (gb=0x18) at /tmp/pahole/gobuffer.h:39 39 return gb->index; (gdb) bt (gdb) frame 1 1042 if (gobuffer__size(&encoder->percpu_secinfo) != 0) (gdb) list 1037 1038 int btf_encoder__encode(struct btf_encoder *encoder) 1039 { 1040 int err; 1041 1042 if (gobuffer__size(&encoder->percpu_secinfo) != 0) 1043 btf_encoder__add_datasec(encoder, PERCPU_SECTION); 1044 1045 /* Empty file, nothing to do, so... done! */ 1046 if (btf__get_nr_types(encoder->btf) == 0) (gdb) print encoder $1 = (struct btf_encoder *) 0x0 [2] https://sourceware.org/git/?p=elfutils.git;a=blob;f=libdwfl/libdwfl.h;h=f98f1d525d94bc7bcfc7c816890de5907ee4bd6d;hb=HEAD#l200 Signed-off-by: Kornilios Kourtis --- dwarf_loader.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/dwarf_loader.c b/dwarf_loader.c index 151bc83..c87378b 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -3268,7 +3268,10 @@ static int cus__process_file(struct cus *cus, struct conf_load *conf, int fd, }; /* Process the one or more modules gleaned from this file. */ - dwfl_getmodules(dwfl, cus__process_dwflmod, &parms, 0); + int err = dwfl_getmodules(dwfl, cus__process_dwflmod, &parms, 0); + if (err) { + return -1; + } // We can't call dwfl_end(dwfl) here, as we keep pointers to strings // allocated by libdw that will be freed at dwfl_end(), so leave this for -- 2.25.1