From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id ZiK9LpZU8mIGryMAWB0awg (envelope-from ) for ; Tue, 09 Aug 2022 08:35:34 -0400 Received: by simark.ca (Postfix, from userid 112) id B32361E5EA; Tue, 9 Aug 2022 08:35:34 -0400 (EDT) Authentication-Results: simark.ca; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.a=rsa-sha256 header.s=default header.b=LanieILa; dkim-atps=neutral X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 450231E13B for ; Tue, 9 Aug 2022 08:35:34 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id AF74F385703C for ; Tue, 9 Aug 2022 12:35:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org AF74F385703C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1660048532; bh=uRRXEGmgUgpcL9R4sSMI7PokWcO6WUXBBEAIr3kfHNk=; h=Date:To:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:Cc:From; b=LanieILafXcJvRnVa0LGg2l8Dgwc1ZM7tUAbaWQDTsP9YT5kAAjEHeBpcfjQ4K8rL VgJDwFNhQILSniaPEGfVUVpdfEaJ3sum/gfut7kyd9IIGXPURdPCOMgZAnn9XpDvyd uglEej7MO8HysEwQYbSk3P1hfgssxlLj5qA+wj+w= Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by sourceware.org (Postfix) with ESMTPS id 62D0D385735A for ; Tue, 9 Aug 2022 12:35:11 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 62D0D385735A Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 832EE20B4A; Tue, 9 Aug 2022 12:35:10 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 6D53713AA1; Tue, 9 Aug 2022 12:35:10 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id N1Z+GX5U8mIWFQAAMHmgww (envelope-from ); Tue, 09 Aug 2022 12:35:10 +0000 Date: Tue, 9 Aug 2022 14:35:09 +0200 To: gdb-patches@sourceware.org Subject: [PATCH][gdb/symtab] Fix assert in set_length Message-ID: <20220809123507.GA29848@delia.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Tom de Vries via Gdb-patches Reply-To: Tom de Vries Cc: Tom Tromey Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" Hi, When running the included test-case, we run into: ... (gdb) break _start^M read.h:309: internal-error: set_length: \ Assertion `m_length == length' failed.^M ... The problem is that while there are two CUs: ... $ readelf -wi debug-names-missing-cu | grep @ Compilation Unit @ offset 0x0: Compilation Unit @ offset 0x2d: ... the CU table in the .debug_names section only contains the first one: ... CU table: [ 0] 0x0 ... The incomplete CU table makes create_cus_from_debug_names_list set the size of the CU at 0x0 to the actual size of both CUs combined. This eventually leads to the assert, when we read the actual size from the CU header. While having an incomplete CU table in a .debug_names section is incorrect, we need a better failure mode than asserting. The easiest way to fix this is to set the length to 0 (meaning: unkown) in create_cus_from_debug_names_list. This makes the failure mode to accept the incomplete CU table, but to ignore the missing CU. It would be nice to instead reject the .debug_names index, and build a complete CU list, but the point where we find this out is well after dwarf2_initialize_objfile, so it looks rather intrusive to restart at that point. Tested on x86_64-linux. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29453 Any comments? Thanks, - Tom [gdb/symtab] Fix assert in set_length --- gdb/dwarf2/read.c | 4 +- .../gdb.dwarf2/debug-names-missing-cu.exp | 83 ++++++++++++++++++++++ 2 files changed, 86 insertions(+), 1 deletion(-) diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 84faeb45238..6c6ca96f8d9 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -4655,7 +4655,9 @@ create_cus_from_debug_names_list (dwarf2_per_bfd *per_bfd, " ignoring .debug_names.")); return false; } - const ULONGEST length = sect_off_next - sect_off_prev; + /* Note: we're not using length = sect_off_next - sect_off_prev, + to gracefully handle an incomplete CU list. */ + const ULONGEST length = 0; dwarf2_per_cu_data_up per_cu = create_cu_from_index_list (per_bfd, §ion, is_dwz, sect_off_prev, length); diff --git a/gdb/testsuite/gdb.dwarf2/debug-names-missing-cu.exp b/gdb/testsuite/gdb.dwarf2/debug-names-missing-cu.exp new file mode 100644 index 00000000000..5778bef55e8 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/debug-names-missing-cu.exp @@ -0,0 +1,83 @@ +# Copyright 2022 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +load_lib dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +if {![dwarf2_support]} { + return 0 +} + +standard_testfile _start.c debug-names.S + +set func_info_vars \ + [get_func_info _start [list debug additional_flags=-nostartfiles]] + +# Create the DWARF. +set asm_file [standard_output_file $srcfile2] +Dwarf::assemble { + filename $asm_file + add_dummy_cus 0 +} { + global func_info_vars + foreach var $func_info_vars { + global $var + } + + cu { label cu_label } { + compile_unit {{language @DW_LANG_C}} { + subprogram { + {DW_AT_name _start} + {DW_AT_low_pc $_start_start DW_FORM_addr} + {DW_AT_high_pc $_start_end DW_FORM_addr} + } + base_type { + {name int} + {byte_size 4 sdata} + {encoding @DW_ATE_signed} + } + } + } + + # This CU is missing from the cu list in .debug_names. + cu {} { + } + + debug_names {} { + cu cu_label + name _start subprogram cu_label 0xEDDB6232 + name int base_type cu_label 0xB888030 + } +} + +if [prepare_for_testing "failed to prepare" $testfile "${asm_file} ${srcfile}" \ + [list additional_flags=-nostartfiles]] { + return -1 +} + +# Verify that .debug_names section is not ignored. +set index [have_index $binfile] +gdb_assert { [string equal $index "debug_names"] } ".debug_names used" + +# Verify that initially no symtab is expanded. +gdb_test_no_output "maint info symtabs" + +if ![runto _start] { + return -1 +} + +# Verify that breaking on _start actually expanded a symtab, rather than +# falling back on minimal symbols. +gdb_test "maint info symtabs" "name .*" "break _start expanded symtab"