On 16-05-19 17:37, Andrew Burgess wrote:
> * Tom de Vries <tdevries@suse.de> [2019-05-03 11:31:26 +0200]:
> This all sounds good. I have a couple of small suggestions inline
> below...
>
>>
>> ---
>> gdb/dwarf2read.c | 49 +++++++++++++++++++++++++++++++++++++++----------
>> 1 file changed, 39 insertions(+), 10 deletions(-)
>>
>> diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
>> index b0bdecf96f..442b618f6e 100644
>> --- a/gdb/dwarf2read.c
>> +++ b/gdb/dwarf2read.c
>> @@ -1518,8 +1518,14 @@ static unsigned int peek_abbrev_code (bfd *, const gdb_byte *);
>> static struct partial_die_info *load_partial_dies
>> (const struct die_reader_specs *, const gdb_byte *, int);
>>
>> -static struct partial_die_info *find_partial_die (sect_offset, int,
>> - struct dwarf2_cu *);
>> +struct cu_partial_die_info
>> +{
>> + struct dwarf2_cu *cu;
>> + struct partial_die_info *pdi;
>> +};
>
> This needs at least a header comment describing its use, and ideally
> each field documented too.
>
Done.
> I wonder though if you should also provide this with a 2 argument
> constructor, and delete the default constructor, like:
>
> /* blah blah blah... */
>
> struct cu_partial_die_info
> {
> /* mumble.. */
> struct dwarf2_cu *cu;
>
> /* mutter... */
> struct partial_die_info *pdi;
>
> cu_partial_die_info (struct dwarf2_cu *cu,
> struct partial_die_info *pdi)
> : cu (cu),
> pdi (pdi)
> { /* Nothing. */ }
>
> private:
> cu_partial_die_info () = delete;
> };
>
> This will lead to some obvious knock on changes in the rest of the
> code, which I think are probably improvements.
>
I've tried this out, and the only effect was this type of changes:
...
- struct cu_partial_die_info res;
+ struct cu_partial_die_info res (NULL, NULL);
...
So, I've left this out for now.
Committed as below.
Also ok for 8.3 branch?
Thanks,
- Tom
[gdb] Fix heap-use-after-free in typename_concat
When running gdb using AddressSanitizer, and loading a cc1plus binary built
with profiledbootstrap and -flto, we run into a heap-use-after-free error:
...
$ LD_PRELOAD=/usr/lib64/libasan.so.3 ./gdb -batch cc1plus
==26855==ERROR: AddressSanitizer: heap-use-after-free on address \
0x62100ad8a8b0 at pc 0x7f13803cc9e3 bp 0x7ffe55b0d090 sp 0x7ffe55b0c840
READ of size 47 at 0x62100ad8a8b0 thread T0
#0 0x7f13803cc9e2 (/usr/lib64/libasan.so.3+0x3e9e2)
#1 0x5e7a0d in typename_concat gdb/dwarf2read.c:22661
#2 0x5c6437 in partial_die_full_name gdb/dwarf2read.c:8876
#3 0x5c6555 in add_partial_symbol gdb/dwarf2read.c:8893
#4 0x5c6ecf in add_partial_subprogram gdb/dwarf2read.c:9156
#5 0x5c5e90 in scan_partial_symbols gdb/dwarf2read.c:8668
#6 0x5c6c0a in add_partial_namespace gdb/dwarf2read.c:9081
#7 0x5c5f99 in scan_partial_symbols gdb/dwarf2read.c:8702
#8 0x5c48b6 in process_psymtab_comp_unit_reader gdb/dwarf2read.c:8056
#9 0x5c3c1f in init_cutu_and_read_dies gdb/dwarf2read.c:7689
#10 0x5c4c03 in process_psymtab_comp_unit gdb/dwarf2read.c:8140
#11 0x5c58a2 in dwarf2_build_psymtabs_hard gdb/dwarf2read.c:8500
#12 0x5c0d03 in dwarf2_build_psymtabs(objfile*) gdb/dwarf2read.c:6337
#13 0x612359 in read_psyms gdb/elfread.c:1311
#14 0x798a64 in require_partial_symbols(objfile*, int) gdb/psymtab.c:115
#15 0x867d7b in read_symbols gdb/symfile.c:821
#16 0x8683d9 in syms_from_objfile_1 gdb/symfile.c:1000
#17 0x8684a1 in syms_from_objfile gdb/symfile.c:1017
#18 0x868873 in symbol_file_add_with_addrs gdb/symfile.c:1124
#19 0x868b0a in symbol_file_add_from_bfd(bfd*, char const*, \
enum_flags<symfile_add_flag>, std::vector<other_sections, \
std::allocator<other_sections> >*, \
enum_flags<objfile_flag>, objfile*) gdb/symfile.c:1204
#20 0x868b64 in symbol_file_add(char const*, \
enum_flags<symfile_add_flag>, \
std::vector<other_sections, \
std::allocator<other_sections> >*, \
enum_flags<objfile_flag>) gdb/symfile.c:1217
#21 0x868c39 in symbol_file_add_main_1 gdb/symfile.c:1240
#22 0x868bd0 in symbol_file_add_main(char const*, \
enum_flags<symfile_add_flag>) gdb/symfile.c:1231
#23 0x71f1b2 in symbol_file_add_main_adapter gdb/main.c:395
#24 0x71f10e in catch_command_errors gdb/main.c:372
#25 0x71ff5f in captured_main_1 gdb/main.c:1043
#26 0x72045d in captured_main gdb/main.c:1163
#27 0x7204c8 in gdb_main(captured_main_args*) gdb/main.c:1188
#28 0x40fd7d in main gdb/gdb.c:32
#29 0x7f137e300f49 in __libc_start_main (/lib64/libc.so.6+0x20f49)
#30 0x40fc89 in _start (/data/gdb_versions/devel/build/gdb/gdb+0x40fc89)
0x62100ad8a8b0 is located 944 bytes inside of 4064-byte region \
[0x62100ad8a500,0x62100ad8b4e0)
freed by thread T0 here:
#0 0x7f13804523a0 in __interceptor_free (/usr/lib64/libasan.so.3+0xc43a0)
#1 0x435e44 in xfree<void> gdb/common/common-utils.h:60
#2 0xa82c25 in call_freefun libiberty/obstack.c:103
#3 0xa83098 in _obstack_free libiberty/obstack.c:280
#4 0x4367da in auto_obstack::~auto_obstack() gdb/gdb_obstack.h:101
#5 0x5ed72c in dwarf2_cu::~dwarf2_cu() gdb/dwarf2read.c:25341
#6 0x5fb5bb in std::default_delete<dwarf2_cu>::operator()(dwarf2_cu*) const \
/usr/include/c++/7/bits/unique_ptr.h:78
#7 0x5f7334 in std::unique_ptr<dwarf2_cu, \
std::default_delete<dwarf2_cu> >::~unique_ptr() \
/usr/include/c++/7/bits/unique_ptr.h:268
#8 0x5c3ce5 in init_cutu_and_read_dies gdb/dwarf2read.c:7624
#9 0x5c4c03 in process_psymtab_comp_unit gdb/dwarf2read.c:8140
#10 0x5c58a2 in dwarf2_build_psymtabs_hard gdb/dwarf2read.c:8500
#11 0x5c0d03 in dwarf2_build_psymtabs(objfile*) gdb/dwarf2read.c:6337
#12 0x612359 in read_psyms gdb/elfread.c:1311
#13 0x798a64 in require_partial_symbols(objfile*, int) gdb/psymtab.c:115
#14 0x867d7b in read_symbols gdb/symfile.c:821
#15 0x8683d9 in syms_from_objfile_1 gdb/symfile.c:1000
#16 0x8684a1 in syms_from_objfile gdb/symfile.c:1017
#17 0x868873 in symbol_file_add_with_addrs gdb/symfile.c:1124
#18 0x868b0a in symbol_file_add_from_bfd(bfd*, char const*, \
enum_flags<symfile_add_flag>, std::vector<other_sections, \
std::allocator<other_sections> >*, \
enum_flags<objfile_flag>, objfile*) gdb/symfile.c:1204
#19 0x868b64 in symbol_file_add(char const*, \
enum_flags<symfile_add_flag>, std::vector<other_sections, \
std::allocator<other_sections> >*, \
enum_flags<objfile_flag>) gdb/symfile.c:1217
#20 0x868c39 in symbol_file_add_main_1 gdb/symfile.c:1240
#21 0x868bd0 in symbol_file_add_main(char const*, \
enum_flags<symfile_add_flag>) gdb/symfile.c:1231
#22 0x71f1b2 in symbol_file_add_main_adapter gdb/main.c:395
#23 0x71f10e in catch_command_errors gdb/main.c:372
#24 0x71ff5f in captured_main_1 gdb/main.c:1043
#25 0x72045d in captured_main gdb/main.c:1163
#26 0x7204c8 in gdb_main(captured_main_args*) gdb/main.c:1188
#27 0x40fd7d in main gdb/gdb.c:32
#28 0x7f137e300f49 in __libc_start_main (/lib64/libc.so.6+0x20f49)
previously allocated by thread T0 here:
#0 0x7f13804526b8 in __interceptor_malloc (/usr/lib64/libasan.so.3+0xc46b8)
#1 0x5114b5 in xmalloc gdb/common/common-utils.c:44
#2 0xa82bd5 in call_chunkfun libiberty/obstack.c:94
#3 0xa82eda in _obstack_newchunk libiberty/obstack.c:206
#4 0x477310 in allocate_on_obstack::operator new(unsigned long, obstack*) \
gdb/gdb_obstack.h:117
#5 0x5dea8c in load_partial_dies gdb/dwarf2read.c:18571
#6 0x5c487f in process_psymtab_comp_unit_reader gdb/dwarf2read.c:8054
#7 0x5c3c1f in init_cutu_and_read_dies gdb/dwarf2read.c:7689
#8 0x5c4c03 in process_psymtab_comp_unit gdb/dwarf2read.c:8140
#9 0x5c58a2 in dwarf2_build_psymtabs_hard gdb/dwarf2read.c:8500
#10 0x5c0d03 in dwarf2_build_psymtabs(objfile*) gdb/dwarf2read.c:6337
#11 0x612359 in read_psyms gdb/elfread.c:1311
#12 0x798a64 in require_partial_symbols(objfile*, int) gdb/psymtab.c:115
#13 0x867d7b in read_symbols gdb/symfile.c:821
#14 0x8683d9 in syms_from_objfile_1 gdb/symfile.c:1000
#15 0x8684a1 in syms_from_objfile gdb/symfile.c:1017
#16 0x868873 in symbol_file_add_with_addrs gdb/symfile.c:1124
#17 0x868b0a in symbol_file_add_from_bfd(bfd*, char const*, \
enum_flags<symfile_add_flag>, \
std::vector<other_sections, \
std::allocator<other_sections> >*, \
enum_flags<objfile_flag>, objfile*) gdb/symfile.c:1204
#18 0x868b64 in symbol_file_add(char const*, enum_flags<symfile_add_flag>, \
std::vector<other_sections, \
std::allocator<other_sections> >*, \
enum_flags<objfile_flag>) gdb/symfile.c:1217
#19 0x868c39 in symbol_file_add_main_1 gdb/symfile.c:1240
#20 0x868bd0 in symbol_file_add_main(char const*, \
enum_flags<symfile_add_flag>) gdb/symfile.c:1231
#21 0x71f1b2 in symbol_file_add_main_adapter gdb/main.c:395
#22 0x71f10e in catch_command_errors gdb/main.c:372
#23 0x71ff5f in captured_main_1 gdb/main.c:1043
#24 0x72045d in captured_main gdb/main.c:1163
#25 0x7204c8 in gdb_main(captured_main_args*) gdb/main.c:1188
#26 0x40fd7d in main gdb/gdb.c:32
#27 0x7f137e300f49 in __libc_start_main (/lib64/libc.so.6+0x20f49)
...
This error happens as follows.
The function find_partial_die has a cu argument, but returns a pdi which may
or may not be from that cu:
...
/* Find a partial DIE at OFFSET, which may or may not be in CU,
except in the case of .debug_types DIEs which do not reference
outside their CU (they do however referencing other types via
DW_FORM_ref_sig8). */
static struct partial_die_info *
find_partial_die (sect_offset sect_off, int offset_in_dwz, struct dwarf2_cu *cu)
...
So the pdi returned by find_partial_die here in partial_die_parent_scope may
be from another cu:
...
partial_die_parent_scope (struct partial_die_info *pdi,
struct dwarf2_cu *cu)
{
const char *grandparent_scope;
struct partial_die_info *parent, *real_pdi;
/* We need to look at our parent DIE; if we have a DW_AT_specification,
then this means the parent of the specification DIE. */
real_pdi = pdi;
while (real_pdi->has_specification)
real_pdi = find_partial_die (real_pdi->spec_offset,
real_pdi->spec_is_dwz, cu);
parent = real_pdi->die_parent;
...
in which case both real_pdi and parent will be not from cu, but from another
one, say cu2.
Subsequently, cu's comp_unit_obstack is used to set parent->scope:
...
parent->scope = typename_concat (&cu->comp_unit_obstack,
grandparent_scope,
parent->name, 0, cu);
...
So, we use cu->comp_unit_obstack to assign a value to the scope field of
a pdi belonging to cu2, and when cu is deleted, the scope field points to a
freed value.
Fix this by making find_partial_die return the cu corresponding to the
returned pdi, and handling this at the call sites.
Tested on x86_64-linux.
gdb/ChangeLog:
2019-05-03 Tom de Vries <tdevries@suse.de>
PR gdb/24094
* dwarf2read.c (struct cu_partial_die_info): New struct.
(find_partial_die): Return cu_partial_die_info.
(partial_die_parent_scope, guess_partial_die_structure_name)
(partial_die_info::fixup): Handle new return type of find_partial_die.
---
gdb/dwarf2read.c | 42 ++++++++++++++++++++++++++++++++----------
1 file changed, 32 insertions(+), 10 deletions(-)
@@ -1507,8 +1507,17 @@ static unsigned int peek_abbrev_code (bfd *, const gdb_byte *);
static struct partial_die_info *load_partial_dies
(const struct die_reader_specs *, const gdb_byte *, int);
-static struct partial_die_info *find_partial_die (sect_offset, int,
- struct dwarf2_cu *);
+/* A pair of partial_die_info and compilation unit. */
+struct cu_partial_die_info
+{
+ /* The compilation unit of the partial_die_info. */
+ struct dwarf2_cu *cu;
+ /* A partial_die_info. */
+ struct partial_die_info *pdi;
+};
+
+static struct cu_partial_die_info find_partial_die (sect_offset, int,
+ struct dwarf2_cu *);
static const gdb_byte *read_attribute (const struct die_reader_specs *,
struct attribute *, struct attr_abbrev *,
@@ -8754,14 +8763,19 @@ partial_die_parent_scope (struct partial_die_info *pdi,
{
const char *grandparent_scope;
struct partial_die_info *parent, *real_pdi;
+ struct cu_partial_die_info res;
/* We need to look at our parent DIE; if we have a DW_AT_specification,
then this means the parent of the specification DIE. */
real_pdi = pdi;
while (real_pdi->has_specification)
- real_pdi = find_partial_die (real_pdi->spec_offset,
- real_pdi->spec_is_dwz, cu);
+ {
+ res = find_partial_die (real_pdi->spec_offset,
+ real_pdi->spec_is_dwz, cu);
+ real_pdi = res.pdi;
+ cu = res.cu;
+ }
parent = real_pdi->die_parent;
if (parent == NULL)
@@ -18905,7 +18919,7 @@ dwarf2_cu::find_partial_die (sect_offset sect_off)
outside their CU (they do however referencing other types via
DW_FORM_ref_sig8). */
-static struct partial_die_info *
+static struct cu_partial_die_info
find_partial_die (sect_offset sect_off, int offset_in_dwz, struct dwarf2_cu *cu)
{
struct dwarf2_per_objfile *dwarf2_per_objfile
@@ -18919,7 +18933,7 @@ find_partial_die (sect_offset sect_off, int offset_in_dwz, struct dwarf2_cu *cu)
{
pd = cu->find_partial_die (sect_off);
if (pd != NULL)
- return pd;
+ return { cu, pd };
/* We missed recording what we needed.
Load all dies and try again. */
per_cu = cu->per_cu;
@@ -18967,7 +18981,7 @@ find_partial_die (sect_offset sect_off, int offset_in_dwz, struct dwarf2_cu *cu)
_("could not find partial DIE %s "
"in cache [from module %s]\n"),
sect_offset_str (sect_off), bfd_get_filename (objfile->obfd));
- return pd;
+ return { per_cu->cu, pd };
}
/* See if we can figure out if the class lives in a namespace. We do
@@ -18986,6 +19000,7 @@ guess_partial_die_structure_name (struct partial_die_info *struct_pdi,
struct partial_die_info *real_pdi;
struct partial_die_info *child_pdi;
+ struct cu_partial_die_info res;
/* If this DIE (this DIE's specification, if any) has a parent, then
we should not do this. We'll prepend the parent's fully qualified
@@ -18993,8 +19008,12 @@ guess_partial_die_structure_name (struct partial_die_info *struct_pdi,
real_pdi = struct_pdi;
while (real_pdi->has_specification)
- real_pdi = find_partial_die (real_pdi->spec_offset,
- real_pdi->spec_is_dwz, cu);
+ {
+ res = find_partial_die (real_pdi->spec_offset,
+ real_pdi->spec_is_dwz, cu);
+ real_pdi = res.pdi;
+ cu = res.cu;
+ }
if (real_pdi->die_parent != NULL)
return;
@@ -19039,8 +19058,11 @@ partial_die_info::fixup (struct dwarf2_cu *cu)
if (name == NULL && has_specification)
{
struct partial_die_info *spec_die;
+ struct cu_partial_die_info res;
- spec_die = find_partial_die (spec_offset, spec_is_dwz, cu);
+ res = find_partial_die (spec_offset, spec_is_dwz, cu);
+ spec_die = res.pdi;
+ cu = res.cu;
spec_die->fixup (cu);