[Bug mi/27770] New: crash with interpreter-exec

[Bug mi/27770] New: crash with interpreter-exec

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27770

            Bug ID: 27770
           Summary: crash with interpreter-exec
           Product: gdb
           Version: 10.1
            Status: NEW
          Severity: normal
          Priority: P2
         Component: mi
          Assignee: unassigned at sourceware dot org
          Reporter: tromey at sourceware dot org
  Target Milestone: ---

In bug #27757, we found out that an interpreter-exec command
using a different MI version caused a crash.
The primary problem in that bug was fixed, but I think the
crash deserves its own bug.
See that bug for reproducer instructions, especially comment #4

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[Bug mi/27770] crash with interpreter-exec

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27770

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
It's as simple as:

$ gdb -nx -i=mi3
...
-interpreter-exec mi2 "-data-evaluate-expression 23"

That is, using different versions of MI at the same time.

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[Bug mi/27770] crash with interpreter-exec

[vimacs.hacks at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27770

vimacs.hacks at gmail dot com <vimacs.hacks at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vimacs.hacks at gmail dot com

--- Comment #2 from vimacs.hacks at gmail dot com <vimacs.hacks at gmail dot com> ---
I encountered the same problem when trying to use GDB in Eclipse (hardcoded to
mi2). I use valgrind to debug this problem, and found mi->raw_stdout is
uninitialised:

# start gdbserver with "gdbserver :9999 /bin/ls"

$ valgrind ./gdb/gdb --interpreter=mi2
...
GNU gdb (GDB) 14.0.50.20230516-git
...
1-target-select remote 127.0.0.1:9999
...
2-interpreter-exec mi "monitor set debug 1"
&"monitor set debug 1\n"
@"Debug output enabled.\n"
==80114== Use of uninitialised value of size 8
==80114==    at 0x9CA8BB: gdb_puts(char const*, ui_file*) (utils.c:1812)
==80114==    by 0x6DD25C: captured_mi_execute_command(ui_out*, mi_parse*)
(mi-main.c:1867)
==80114==    by 0x6DD573: mi_execute_command(char const*, int) (mi-main.c:1942)
==80114==    by 0x6C5B29: mi_execute_command_wrapper(char const*)
(mi-interp.c:274)
==80114==    by 0x6C5919: mi_interp::exec(char const*) (mi-interp.c:204)
==80114==    by 0x62D0E0: interp_exec(interp*, char const*) (interps.c:293)
==80114==    by 0x6C5A4C: mi_cmd_interpreter_exec(char const*, char**, int)
(mi-interp.c:241)
==80114==    by 0x6C2480: mi_command_mi::invoke(mi_parse*) const (mi-cmds.c:58)
==80114==    by 0x6DDC65: mi_cmd_execute(mi_parse*) (mi-main.c:2114)
==80114==    by 0x6DD0AA: captured_mi_execute_command(ui_out*, mi_parse*)
(mi-main.c:1818)
==80114==    by 0x6DD573: mi_execute_command(char const*, int) (mi-main.c:1942)
==80114==    by 0x6C5B29: mi_execute_command_wrapper(char const*)
(mi-interp.c:274)
==80114== 
==80114== Invalid read of size 8
==80114==    at 0x9CA8BB: gdb_puts(char const*, ui_file*) (utils.c:1812)
==80114==    by 0x6DD25C: captured_mi_execute_command(ui_out*, mi_parse*)
(mi-main.c:1867)
==80114==    by 0x6DD573: mi_execute_command(char const*, int) (mi-main.c:1942)
==80114==    by 0x6C5B29: mi_execute_command_wrapper(char const*)
(mi-interp.c:274)
==80114==    by 0x6C5919: mi_interp::exec(char const*) (mi-interp.c:204)
==80114==    by 0x62D0E0: interp_exec(interp*, char const*) (interps.c:293)
==80114==    by 0x6C5A4C: mi_cmd_interpreter_exec(char const*, char**, int)
(mi-interp.c:241)
==80114==    by 0x6C2480: mi_command_mi::invoke(mi_parse*) const (mi-cmds.c:58)
==80114==    by 0x6DDC65: mi_cmd_execute(mi_parse*) (mi-main.c:2114)
==80114==    by 0x6DD0AA: captured_mi_execute_command(ui_out*, mi_parse*)
(mi-main.c:1818)
==80114==    by 0x6DD573: mi_execute_command(char const*, int) (mi-main.c:1942)
==80114==    by 0x6C5B29: mi_execute_command_wrapper(char const*)
(mi-interp.c:274)
==80114==  Address 0x0 is not stack'd, malloc'd or (recently) free'd

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[Bug mi/27770] crash with interpreter-exec

[vimacs.hacks at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27770

--- Comment #3 from vimacs.hacks at gmail dot com <vimacs.hacks at gmail dot com> ---
I seem to know why this can crash. In the following code:

std::unique_ptr<mi_ui_out>
mi_out_new (const char *mi_version)
{
  if (streq (mi_version, INTERP_MI4) ||  streq (mi_version, INTERP_MI))
    return std::make_unique<mi_ui_out> (4);

  if (streq (mi_version, INTERP_MI3))
    return std::make_unique<mi_ui_out> (3);

  if (streq (mi_version, INTERP_MI2))
    return std::make_unique<mi_ui_out> (2);

  return nullptr;
}

Different MI version makes a different mi_ui_out, so when -interpreter-exec
gives a different version than the one in command line, the ui_out object
cannot be found.

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