From patchwork Wed Jul 4 06:54:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom de Vries X-Patchwork-Id: 28222 Received: (qmail 89404 invoked by alias); 4 Jul 2018 06:54:49 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 88015 invoked by uid 89); 4 Jul 2018 06:54:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_PASS autolearn=ham version=3.3.2 spammy=behind X-HELO: mx1.suse.de Received: from mx2.suse.de (HELO mx1.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 04 Jul 2018 06:54:45 +0000 Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6AB75ADE7; Wed, 4 Jul 2018 06:54:43 +0000 (UTC) Date: Wed, 4 Jul 2018 08:54:45 +0200 From: Tom de Vries To: Pedro Alves Cc: gdb-patches@sourceware.org Subject: [PATCH][gdb/symtab] Fix version check in dwarf compilation unit header Message-ID: <20180704065445.72vpuyllx7ze7kfp@delia> References: <20180619090024.c2yqabvk6oujs6dm@localhost.localdomain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170912 (1.9.0) X-IsSubscribed: yes [ was: Subject: Re: [PATCH][gdb/testsuite] Fix error message test in dw2-error.exp ] On Tue, Jul 03, 2018 at 03:59:17PM +0100, Pedro Alves wrote: > On 06/19/2018 10:00 AM, Tom de Vries wrote: > > > the executable used in dw2-error.exp is compiled from a .s that was generated > > with dwarf2 debug information but has been hand-edited to set the version in > > the compilation unit header to 0x99: > > ... > > .Ldebug_info0: > > .long 0x4e # Length of Compilation Unit Info > > .value 0x99 # DWARF version number > > .long .Ldebug_abbrev0 # Offset Into Abbrev. Section > > ... > > > > Consequently, dwarf2read.c:read_comp_unit_head() interprets the compilation > > unit header as dwarf5, > > > That right there looks like the real bug to me. > > I went looking for the history behind the testcase, and > got surprised that the testcase is expecting that "wrong unit_type in > compilation unit header" error instead of the same error that had been > reported in the original bug report at > : > > ~~~~~ > Dwarf Error: wrong version in compilation unit header (is 4, should be 2) [in module ....build/gdb/gdb] > ~~~~~ > > read_and_check_comp_unit_head calls error_check_comp_unit_head > after calling read_comp_unit_head, and thus AFAICT error_check_comp_unit_head > would error out with the "wrong version" error, the one that had been > reported in the original bug report. That seems like a much better > error to me. > > static void > error_check_comp_unit_head (struct dwarf2_per_objfile *dwarf2_per_objfile, > struct comp_unit_head *header, > struct dwarf2_section_info *section, > struct dwarf2_section_info *abbrev_section) > { > const char *filename = get_section_file_name (section); > > if (header->version < 2 || header->version > 5) > error (_("Dwarf Error: wrong version in compilation unit header " > "(is %d, should be 2, 3, 4 or 5) [in module %s]"), header->version, > filename); > > > > So it seems to me that read_comp_unit_head shouldn't be > trying to interpret contents of a dwarf version that > gdb doesn't understand. Seems like that error_check_comp_unit_head > version check is too late? How about moving it into > read_and_check_comp_unit_head? Of course, the testcase would then > be adjusted to expect the new message, and it would expect 153/0x99 > exactly instead of any number, which ensures that gdb reads and > prints the version number correctly. > Agreed, that analysis makes sense. OK for trunk? Thanks, - Tom [gdb/symtab] Fix version check in dwarf compilation unit header The version check of the dwarf compilation unit header in error_check_comp_unit_head is done too late, and consequently dwarf code with an unsupported version in the compilation unit header is interpreted as dwarf5 code in read_comp_unit_head. Fixed by moving the check earlier. Build and reg-tested on x86_64-linux. 2018-07-04 Tom de Vries * dwarf2read.c (error_check_comp_unit_head): Move dwarf version check ... (read_comp_unit_head): ... here. * gdb.dwarf2/dw2-error.exp: Update expected error message. --- gdb/dwarf2read.c | 9 ++++----- gdb/testsuite/gdb.dwarf2/dw2-error.exp | 2 +- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 9f6d34f1fe..372f45ee17 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -6308,6 +6308,10 @@ read_comp_unit_head (struct comp_unit_head *cu_header, cu_header->offset_size = (bytes_read == 4) ? 4 : 8; info_ptr += bytes_read; cu_header->version = read_2_bytes (abfd, info_ptr); + if (cu_header->version < 2 || cu_header->version > 5) + error (_("Dwarf Error: wrong version in compilation unit header " + "(is %d, should be 2, 3, 4 or 5) [in module %s]"), + cu_header->version, filename); info_ptr += 2; if (cu_header->version < 5) switch (section_kind) @@ -6410,11 +6414,6 @@ error_check_comp_unit_head (struct dwarf2_per_objfile *dwarf2_per_objfile, { const char *filename = get_section_file_name (section); - if (header->version < 2 || header->version > 5) - error (_("Dwarf Error: wrong version in compilation unit header " - "(is %d, should be 2, 3, 4 or 5) [in module %s]"), header->version, - filename); - if (to_underlying (header->abbrev_sect_off) >= dwarf2_section_size (dwarf2_per_objfile->objfile, abbrev_section)) error (_("Dwarf Error: bad offset (%s) in compilation unit header " diff --git a/gdb/testsuite/gdb.dwarf2/dw2-error.exp b/gdb/testsuite/gdb.dwarf2/dw2-error.exp index e22667dea5..8c162a0898 100644 --- a/gdb/testsuite/gdb.dwarf2/dw2-error.exp +++ b/gdb/testsuite/gdb.dwarf2/dw2-error.exp @@ -41,7 +41,7 @@ gdb_test_no_output "set breakpoint pending off" # First test that reading symbols fails. gdb_test "file $binfile" \ - {Reading symbols.*Dwarf Error: wrong unit_type in compilation unit header \(is 0, should be 1 or 2\).*} \ + {Reading symbols.*Dwarf Error: wrong version in compilation unit header \(is 153, should be 2, 3, 4 or 5\).*} \ "file $testfile" # Now check that we can still break given the minimal symbol.