From a7308ce01effdd143bfe5e3c7350fa2d5606d12b Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Sat, 6 Mar 2021 09:26:39 -0700 Subject: [PATCH] Avoid crash on missing dwz file If DWARF contains a reference to a "dwz" file, but there is no .gnu_debugaltlink section, then gdb will crash. This happens because dwarf2_get_dwz_file will return NULL, but some callers do not expect this. This patch changes dwarf2_get_dwz_file so that callers can require a dwz file. Then, it updates the callers that are attempting to process references to the dwz file to require one. This includes a new testcase. The dwarf.exp changes don't handle the new forms exactly correctly -- they are only handled well enough to let this test case complete. gdb/ChangeLog 2021-03-06 Tom Tromey * dwarf2/read.h (dwarf2_get_dwz_file): Add 'require' parameter. * dwarf2/read.c (dwarf2_get_dwz_file): Add 'require' parameter. (get_abbrev_section_for_cu, read_attribute_value) (get_debug_line_section): Update. * dwarf2/macro.c (dwarf_decode_macro_bytes): Update. gdb/testsuite/ChangeLog 2021-03-06 Tom Tromey * lib/dwarf.exp (_handle_DW_FORM): Treat DW_FORM_GNU_ref_alt and DW_FORM_GNU_strp_alt like DW_FORM_sec_offset. * gdb.dwarf2/dwznolink.exp: New file. --- gdb/ChangeLog | 8 ++++ gdb/dwarf2/macro.c | 6 ++- gdb/dwarf2/read.c | 14 +++--- gdb/dwarf2/read.h | 13 +++--- gdb/testsuite/ChangeLog | 6 +++ gdb/testsuite/gdb.dwarf2/dwznolink.exp | 60 ++++++++++++++++++++++++++ gdb/testsuite/lib/dwarf.exp | 4 +- 7 files changed, 97 insertions(+), 14 deletions(-) create mode 100644 gdb/testsuite/gdb.dwarf2/dwznolink.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9032dd60ff9..00619cc4cd8 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2021-03-06 Tom Tromey + + * dwarf2/read.h (dwarf2_get_dwz_file): Add 'require' parameter. + * dwarf2/read.c (dwarf2_get_dwz_file): Add 'require' parameter. + (get_abbrev_section_for_cu, read_attribute_value) + (get_debug_line_section): Update. + * dwarf2/macro.c (dwarf_decode_macro_bytes): Update. + 2021-03-06 Tom Tromey * dwarf2/sect-names.h (struct dwarf2_section_names) : New diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c index afe2f91168b..2ecebe6173c 100644 --- a/gdb/dwarf2/macro.c +++ b/gdb/dwarf2/macro.c @@ -509,7 +509,8 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile, || macinfo_type == DW_MACRO_undef_sup || section_is_dwz) { - dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd); + dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd, + true); body = dwz->read_string (objfile, str_offset); } @@ -693,7 +694,8 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile, if (macinfo_type == DW_MACRO_import_sup) { - dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd); + dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd, + true); dwz->macro.read (objfile); diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index e9cd9293a46..65e2047ef32 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -2285,7 +2285,7 @@ dwz_search_other_debugdirs (std::string &filename, bfd_byte *buildid, /* See dwarf2read.h. */ struct dwz_file * -dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd) +dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd, bool require) { bfd_size_type buildid_len_arg; size_t buildid_len; @@ -2301,7 +2301,11 @@ dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd) if (data == NULL) { if (bfd_get_error () == bfd_error_no_error) - return NULL; + { + if (!require) + return nullptr; + error (_("could not read '.gnu_debugaltlink' section")); + } error (_("could not read '.gnu_debugaltlink' section: %s"), bfd_errmsg (bfd_get_error ())); } @@ -6308,7 +6312,7 @@ get_abbrev_section_for_cu (struct dwarf2_per_cu_data *this_cu) dwarf2_per_bfd *per_bfd = this_cu->per_bfd; if (this_cu->is_dwz) - abbrev = &dwarf2_get_dwz_file (per_bfd)->abbrev; + abbrev = &dwarf2_get_dwz_file (per_bfd, true)->abbrev; else abbrev = &per_bfd->abbrev; @@ -20654,7 +20658,7 @@ read_attribute_value (const struct die_reader_specs *reader, /* FALLTHROUGH */ case DW_FORM_GNU_strp_alt: { - dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd); + dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd, true); LONGEST str_offset = cu_header->read_offset (abfd, info_ptr, &bytes_read); @@ -21252,7 +21256,7 @@ get_debug_line_section (struct dwarf2_cu *cu) section = &cu->dwo_unit->dwo_file->sections.line; else if (cu->per_cu->is_dwz) { - dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd); + dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd, true); section = &dwz->line; } diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h index c7f6a111b8c..b974fe46ef4 100644 --- a/gdb/dwarf2/read.h +++ b/gdb/dwarf2/read.h @@ -633,11 +633,14 @@ struct signatured_type struct dwo_unit *dwo_unit; }; -/* Open the separate '.dwz' debug file, if needed. Return NULL if - there is no .gnu_debugaltlink section in the file. Error if there - is such a section but the file cannot be found. */ - -extern dwz_file *dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd); +/* Open the separate '.dwz' debug file, if needed. If there is no + .gnu_debugaltlink section in the file, then the result depends on + REQUIRE: if REQUIRE is true, then error; if REQUIRE is false, + return NULL. Always error if there is such a section but the file + cannot be found. */ + +extern dwz_file *dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd, + bool require = false); /* Return the type of the DIE at DIE_OFFSET in the CU named by PER_CU. */ diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index b7c2e7222ab..ecbb768a423 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2021-03-06 Tom Tromey + + * lib/dwarf.exp (_handle_DW_FORM): Treat DW_FORM_GNU_ref_alt and + DW_FORM_GNU_strp_alt like DW_FORM_sec_offset. + * gdb.dwarf2/dwznolink.exp: New file. + 2021-03-05 Mark Wielaard * lib/valgrind.exp (vgdb_start): Add --wait=1 to vgdbcmd. diff --git a/gdb/testsuite/gdb.dwarf2/dwznolink.exp b/gdb/testsuite/gdb.dwarf2/dwznolink.exp new file mode 100644 index 00000000000..98976d7e59c --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dwznolink.exp @@ -0,0 +1,60 @@ +# Copyright 2021 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 +} + +# No remote host testing either. +if {[is_remote host]} { + return 0 +} + +standard_testfile main.c dwznolink.S + +set asm_file [standard_output_file $srcfile2] + +# The DWARF should contain a reference to a supplementary ("dwz") +# file, but the section that links to the file should be missing. At +# one point, this caused gdb crashes. +Dwarf::assemble $asm_file { + cu {} { + compile_unit {{language @DW_LANG_C}} { + constant { + {name 0 DW_FORM_GNU_strp_alt} + {type 97 DW_FORM_GNU_ref_alt} + {const_value 99 data1} + } + } + } +} + +# We can't use prepare_for_testing here because we need to check the +# 'file' command's output. +if {[build_executable $testfile.exp $testfile \ + [list $srcfile $asm_file] {nodebug quiet}]} { + return -1 +} + +gdb_exit +gdb_start +gdb_reinitialize_dir $srcdir/$subdir + +gdb_test "file -readnow $binfile" \ + "could not read '.gnu_debugaltlink' section" \ + "file $testfile" diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp index c1c07be0b98..f8fbd381810 100644 --- a/gdb/testsuite/lib/dwarf.exp +++ b/gdb/testsuite/lib/dwarf.exp @@ -456,6 +456,8 @@ namespace eval Dwarf { _op .${size}byte $value } + DW_FORM_GNU_ref_alt - + DW_FORM_GNU_strp_alt - DW_FORM_sec_offset { variable _cu_offset_size _op .${_cu_offset_size}byte $value @@ -553,8 +555,6 @@ namespace eval Dwarf { DW_FORM_GNU_addr_index - DW_FORM_GNU_str_index - - DW_FORM_GNU_ref_alt - - DW_FORM_GNU_strp_alt - default { error "unhandled form $form" -- 2.30.2