From: Tom Tromey <tom@tromey.com>
To: Tom Tromey <tom@tromey.com>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH 3/5] Avoid crash on missing dwz file
Date: Sun, 21 Feb 2021 10:19:28 -0700 [thread overview]
Message-ID: <87mtvxs5i7.fsf@tromey.com> (raw)
In-Reply-To: <87v9als839.fsf@tromey.com> (Tom Tromey's message of "Sun, 21 Feb 2021 09:23:38 -0700")
Tom> I didn't write a test for this, but it should probably have one, so I
Tom> will.
Here's the updated patch.
Tom
commit be6b917e5997b2c5ed0ced04f0363e02e7e430bd
Author: Tom Tromey <tom@tromey.com>
Date: Sat Feb 20 19:41:14 2021 -0700
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
2021-02-20 Tom Tromey <tom@tromey.com>
* 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
2021-02-21 Tom Tromey <tom@tromey.com>
* 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.
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index c9e1d0f4b02..89ca0daf76e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2021-02-20 Tom Tromey <tom@tromey.com>
+
+ * 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.
+
2021-02-20 Tom Tromey <tom@tromey.com>
* dwarf2/sect-names.h (struct dwarf2_section_names) <matches>: 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 0347f91947e..6a755f716d1 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -2279,7 +2279,7 @@ 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;
@@ -2295,7 +2295,11 @@ 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 ()));
}
@@ -6300,7 +6304,7 @@ 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;
@@ -20515,7 +20519,7 @@ 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);
@@ -21113,7 +21117,7 @@ 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 d2bae5a7ee8..86ac6b50cc0 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 70b836b8c2f..27f475525ac 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2021-02-21 Tom Tromey <tom@tromey.com>
+
+ * 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.
+
2021-02-18 Andrew Burgess <andrew.burgess@embecosm.com>
* gdb.arch/i386-biarch-core.exp: Add target check.
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 <http://www.gnu.org/licenses/>.
+
+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"
next prev parent reply other threads:[~2021-02-21 17:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-21 3:16 [PATCH 0/5] Some minor dwz-handling improvements & cleanups Tom Tromey
2021-02-21 3:16 ` [PATCH 1/5] Create new file dwarf2/sect-names.h Tom Tromey
2021-02-21 3:16 ` [PATCH 2/5] Change section_is_p to a method on dwarf2_section_names Tom Tromey
2021-02-21 3:16 ` [PATCH 3/5] Avoid crash on missing dwz file Tom Tromey
2021-02-21 16:23 ` Tom Tromey
2021-02-21 17:19 ` Tom Tromey [this message]
2021-02-21 3:16 ` [PATCH 4/5] Include scoped_fd.h in debuginfod-support.h Tom Tromey
2021-02-21 3:16 ` [PATCH 5/5] Move dwarf2_get_dwz_file to dwarf2/dwz.h Tom Tromey
2021-03-06 16:28 ` [PATCH 0/5] Some minor dwz-handling improvements & cleanups Tom Tromey
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