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* [Bug python/28856] New: Python pretty printer causes stack overflow when printing frame arguments
@ 2022-02-03 11:45 jwakely.gcc at gmail dot com
  2022-02-03 11:46 ` [Bug python/28856] " jwakely.gcc at gmail dot com
                   ` (14 more replies)
  0 siblings, 15 replies; 16+ messages in thread
From: jwakely.gcc at gmail dot com @ 2022-02-03 11:45 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=28856

            Bug ID: 28856
           Summary: Python pretty printer causes stack overflow when
                    printing frame arguments
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: python
          Assignee: unassigned at sourceware dot org
          Reporter: jwakely.gcc at gmail dot com
  Target Milestone: ---

Compile one C++ source file, as follows:

struct category
{
  virtual const char* name() const = 0;
};

struct cat : category
{
  const char* name() const { return "miaow"; }
};

category* getcat() { static cat c; return &c; }

struct error_code
{
  error_code(int i = 0) : m_value(i), m_cat(getcat()) { }

  void assign(int i) { m_value = i; }
  int value() const { return m_value; }

  int m_value;
  category* m_cat;
};

int f(error_code& ec)
{
  ec.assign(1);
  return ec.value();
}

int g(error_code& ec)
{
  return f(ec);
}

int main()
{
  error_code ec;
  return g(ec);
}



Add one Python file:

class ErrorCodePrinter:
    "print an error_code"

    def __init__ (self, val):
        self.val = val

    @staticmethod
    def _category_name(cat):
        "Call the virtual function that overrides category::name()"
        gdb.set_convenience_variable('__cat', cat)
        return gdb.parse_and_eval('$__cat->name()').string()

    def to_string (self):
        value = self.val['m_value']
        category = self._category_name(self.val['m_cat'])
        return 'error_code = {"%s": %d}' % (category, value)

def ec_lookup_function(val):
    typ = val.type
    if typ.code == gdb.TYPE_CODE_REF:
        typ = typ.target()
    if str(typ) == 'error_code':
        return ErrorCodePrinter(val)
    return None

gdb.pretty_printers.append(ec_lookup_function)




Prepare an executable:

g++ -g ec.cc -o ec

And bake in the oven until it catches fire:

gdb -q -iex "add-auto-load-safe-path $PWD/ec-gdb.py" -ex start -ex n -ex 'p
&ec' -ex step -ex step -ex n -ex up -ex up  ec


Reading symbols from ec...
Temporary breakpoint 1 at 0x40115e: file ec.C, line 37.
Starting program: /tmp/ec 

Temporary breakpoint 1, main () at ec.C:37
37        error_code ec;
38        return g(ec);
$1 = (error_code *) 0x7fffffffd790
g (ec=error_code = {"miaow": 0}) at ec.C:32
32        return f(ec);
f (ec=error_code = {"miaow": 0}) at ec.C:26
26        ec.assign(1);
27        return ec.value();
#1  0x0000000000401154 in g (ec=

Fatal signal: Segmentation fault
----- Backtrace -----
0x4bcd33 gdb_internal_backtrace_1
        /home/jwakely/src/binutils-gdb/gdb/bt-utils.c:121
0x4bcd33 _Z22gdb_internal_backtracev
        /home/jwakely/src/binutils-gdb/gdb/bt-utils.c:164
0x5b32b1 handle_fatal_signal
        /home/jwakely/src/binutils-gdb/gdb/event-top.c:896
0x5b33f4 handle_sigsegv
        /home/jwakely/src/binutils-gdb/gdb/event-top.c:969
0x7f8d6d648a1f ???
        ../sysdeps/unix/sysv/linux/sigaction.c:665
0x4b7ba5 _ZN22scoped_debug_start_endC2ERbPKcS2_S2_S2_S2_z
        /home/jwakely/src/binutils-gdb/gdb/../gdbsupport/common-debug.h:108
0x5cb846 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:181
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5cb879 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:184
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5cb879 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:184
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5cb879 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:184
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5cb879 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:184


[... several thousand more frames ...]
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5cb879 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:184
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5cb879 _Z26frame_unwind_find_by_frameP10frame_infoPPv
        /home/jwakely/src/binutils-gdb/gdb/frame-unwind.c:184
0x5ce738 _Z17frame_unwind_archP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2896
0x5ce784 frame_unwind_pc
        /home/jwakely/src/binutils-gdb/gdb/frame.c:944
0x5ce8cb _Z12get_frame_pcP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2571
0x5ce8cb _Z26get_frame_address_in_blockP10frame_info
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2601
0x55727c dwarf2_frame_cache
        /home/jwakely/src/binutils-gdb/gdb/dwarf2/frame.c:903
0x558303 dwarf2_frame_prev_register
        /home/jwakely/src/binutils-gdb/gdb/dwarf2/frame.c:1136
0x5cee9b _Z27frame_unwind_register_valueP10frame_infoi
        /home/jwakely/src/binutils-gdb/gdb/frame.c:1233
0x5cf23a _Z21frame_register_unwindP10frame_infoiPiS1_P9lval_typePmS1_Ph
        /home/jwakely/src/binutils-gdb/gdb/frame.c:1143
0x5cf5c8 _Z21frame_unwind_registerP10frame_infoiPh
        /home/jwakely/src/binutils-gdb/gdb/frame.c:1199
0x5fe4e0 i386_unwind_pc
        /home/jwakely/src/binutils-gdb/gdb/i386-tdep.c:1970
0x5ce78f frame_unwind_pc
        /home/jwakely/src/binutils-gdb/gdb/frame.c:948
0x5ce869 _Z25get_frame_pc_if_availableP10frame_infoPm
        /home/jwakely/src/binutils-gdb/gdb/frame.c:2582
0x761b40
_Z16print_frame_infoRK19frame_print_optionsP10frame_infoi10print_whatii
        /home/jwakely/src/binutils-gdb/gdb/stack.c:1185
0x76246b _Z17print_stack_frameP10frame_infoi10print_whati
        /home/jwakely/src/binutils-gdb/gdb/stack.c:366
0x762502 _Z26print_stack_frame_to_uioutP6ui_outP10frame_infoi10print_whati
        /home/jwakely/src/binutils-gdb/gdb/stack.c:345
0x4eff7a cli_on_user_selected_context_changed
        /home/jwakely/src/binutils-gdb/gdb/cli/cli-interp.c:277
0x764463 _ZNKSt8functionIFv10enum_flagsI23user_selected_what_flagEEEclES2_
        /usr/include/c++/11/bits/std_function.h:560
0x764463
_ZNK3gdb9observers10observableIJ10enum_flagsI23user_selected_what_flagEEE6notifyES4_
        /home/jwakely/src/binutils-gdb/gdb/../gdbsupport/observable.h:150
0x764463 up_command
        /home/jwakely/src/binutils-gdb/gdb/stack.c:2690
0x4ee2a4 _Z8cmd_funcP16cmd_list_elementPKci
        /home/jwakely/src/binutils-gdb/gdb/cli/cli-decode.c:2459
0x7bdbe1 _Z15execute_commandPKci
        /home/jwakely/src/binutils-gdb/gdb/top.c:670
0x66dcd2 catch_command_errors
        /home/jwakely/src/binutils-gdb/gdb/main.c:523
0x66dd9f execute_cmdargs
        /home/jwakely/src/binutils-gdb/gdb/main.c:618
0x66f4b4 captured_main_1
        /home/jwakely/src/binutils-gdb/gdb/main.c:1317
0x66ff5a captured_main
        /home/jwakely/src/binutils-gdb/gdb/main.c:1338
0x66ff5a _Z8gdb_mainP18captured_main_args
        /home/jwakely/src/binutils-gdb/gdb/main.c:1363
0x431624 main
        /home/jwakely/src/binutils-gdb/gdb/gdb.c:32
---------------------
A fatal error internal to GDB has been detected, further
debugging is not possible.  GDB will now terminate.

This is a bug, please report it.  For instructions, see:
<https://www.gnu.org/software/gdb/bugs/>.

Segmentation fault (core dumped)

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^ permalink raw reply	[flat|nested] 16+ messages in thread
end of thread, other threads:[~2024-01-13 18:50 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-03 11:45 [Bug python/28856] New: Python pretty printer causes stack overflow when printing frame arguments jwakely.gcc at gmail dot com
2022-02-03 11:46 ` [Bug python/28856] " jwakely.gcc at gmail dot com
2022-02-03 11:49 ` jwakely.gcc at gmail dot com
2022-02-03 12:02 ` fweimer at redhat dot com
2022-02-03 19:01 ` ssbssa at sourceware dot org
2022-02-03 20:50 ` jwakely.gcc at gmail dot com
2022-02-03 21:15 ` ssbssa at sourceware dot org
2022-02-03 21:29 ` simark at simark dot ca
2022-02-03 22:19 ` jwakely.gcc at gmail dot com
2022-02-07 17:51 ` blarsen at redhat dot com
2022-03-21 13:23 ` cvs-commit at gcc dot gnu.org
2022-03-24 14:28 ` simon.marchi at polymtl dot ca
2022-10-10 10:14 ` cvs-commit at gcc dot gnu.org
2022-10-10 10:23 ` blarsen at redhat dot com
2023-08-03 15:59 ` tromey at sourceware dot org
2024-01-13 18:50 ` ssbssa at sourceware dot org

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