File gdb-symtab-fix-segfault-in-search_one_symtab.patch of Package gdb
[gdb/symtab] Fix segfault in search_one_symtab
PR28539 describes a segfault in lambda function search_one_symtab due to
psymbol_functions::expand_symtabs_matching calling expansion_notify with a
nullptr symtab:
...
struct compunit_symtab *symtab =
psymtab_to_symtab (objfile, ps);
if (expansion_notify != NULL)
if (!expansion_notify (symtab))
return false;
...
This happens as follows. The partial symtab ps is a dwarf2_include_psymtab
for some header file:
...
(gdb) p ps.filename
$5 = 0x64fcf80 "/usr/include/c++/11/bits/stl_construct.h"
...
The includer of ps is a shared symtab for a partial unit, with as user:
...
(gdb) p ps.includer().user.filename
$11 = 0x64fc9f0 \
"/usr/src/debug/llvm13-13.0.0-1.2.x86_64/tools/clang/lib/AST/Decl.cpp"
...
The call to psymtab_to_symtab expands the Decl.cpp symtab (and consequently
the shared symtab), but returns nullptr because:
...
struct dwarf2_include_psymtab : public partial_symtab
{
...
compunit_symtab *get_compunit_symtab (struct objfile *objfile) const override
{
return nullptr;
}
...
Fix this by returning the Decl.cpp symtab instead, which fixes the segfault
in the PR.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28539
---
gdb/dwarf2/read.c | 5 +-
.../gdb.dwarf2/dw2-symtab-includes-lookup.exp | 101 +++++++++++++++++++++
2 files changed, 105 insertions(+), 1 deletion(-)
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index e73c0855fc1..ea6c6344247 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -5756,7 +5756,10 @@ struct dwarf2_include_psymtab : public partial_symtab
compunit_symtab *get_compunit_symtab (struct objfile *objfile) const override
{
- return nullptr;
+ compunit_symtab *cust = includer ()->get_compunit_symtab (objfile);
+ while (cust != nullptr && cust->user != nullptr)
+ cust = cust->user;
+ return cust;
}
private:
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-symtab-includes-lookup.exp b/gdb/testsuite/gdb.dwarf2/dw2-symtab-includes-lookup.exp
new file mode 100644
index 00000000000..7228f85c9bb
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-symtab-includes-lookup.exp
@@ -0,0 +1,101 @@
+# 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/>.
+
+# Lookup a type in a partial unit with DW_AT_stmt_list.
+#
+# The test-case is setup such that the partial symtab expansion route is
+# .h partial symtab -> shared partial symtab -> toplevel symtab.
+#
+# That is, the partial symtabs (as displayed by maint print objfiles) are:
+#
+# ../sysdeps/x86_64/crtn.S at 0x3d944e0^M
+# elf-init.c at 0x3d94440^M
+# dw2-symtab-includes.h at 0x3d7c7a0^M
+# <unknown> at 0x31ef870^M
+# bla.c at 0x33985f0^M
+# ../sysdeps/x86_64/crti.S at 0x33e9a00^M
+# init.c at 0x33fa600^M
+# ../sysdeps/x86_64/start.S at 0x33f3fd0^M
+#
+# and the expansion of dw2-symtab-includes.h triggers the expansion of its
+# includer <unknown>, which triggers expansion of user bla.c.
+#
+# The problem in PR28539 was that after expansion of dw2-symtab-includes.h
+# the expansion_notify function in psymbol_functions::expand_symtabs_matching
+# should be called with the bla.c symtab, but instead it got called with
+# nullptr, which caused a segfault.
+
+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 main.c .S
+
+# Create the DWARF.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ declare_labels partial_label lines_label
+ global srcdir subdir srcfile
+
+ cu {} {
+ partial_label: partial_unit {
+ {stmt_list ${lines_label} DW_FORM_sec_offset}
+ } {
+ DW_TAG_base_type {
+ {DW_AT_byte_size 4 DW_FORM_sdata}
+ {DW_AT_encoding @DW_ATE_signed}
+ {DW_AT_name myint}
+ }
+ }
+ }
+
+ cu {} {
+ compile_unit {
+ {language @DW_LANG_C}
+ {DW_AT_name bla.c}
+ } {
+ imported_unit {
+ {import $partial_label ref_addr}
+ }
+ }
+ }
+
+ lines {version 2} lines_label {
+ include_dir "${srcdir}/${subdir}"
+ file_name "dw2-symtab-includes.h" 1
+ program {
+ {DW_LNS_advance_line 1}
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" $testfile \
+ "${asm_file} ${srcfile}" {}] } {
+ return -1
+}
+
+# Check that no symtabs are expanded.
+set test "no symtabs expanded"
+if { [readnow] } {
+ unsupported $test
+ return -1
+}
+gdb_test_no_output "maint info symtabs" $test
+
+# Lookup myint. Regression test for PR28539.
+gdb_test "ptype myint" "type = myint"
