From 73aa9ef81be869176814cac635723e920f7ca612 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Thu, 8 Jun 2023 14:06:45 -0600 Subject: [PATCH] Remove unchecked casts to mi_interp Simon noticed a crash that could be caused via new Python gdb.execute_mi function. Looking into this, I found a few unchecked casts to mi_interp, like: - struct mi_interp *mi = (struct mi_interp *) command_interp (); This patch replaces all such casts with safer variants. For -gdb-exit and mi_load_progress, I chose to have the functions simply not generate any output. It didn't seem useful to do so. Some casts I eliminated by adding a parameter to a function. Then, in mi_execute_command, I changed the code to use gdb::checked_static_cast. This is appropriate because this particular overload can only be called by the MI interpreter. There does not seem to be a very good way to test -gdb-exit. Regression tested on x86-64 Fedora 36. --- gdb/mi/mi-interp.c | 9 --------- gdb/mi/mi-interp.h | 9 +++++++++ gdb/mi/mi-main.c | 48 +++++++++++++++++++++++++++++----------------- 3 files changed, 39 insertions(+), 27 deletions(-) diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c index a8de62ba630..0e51c884a65 100644 --- a/gdb/mi/mi-interp.c +++ b/gdb/mi/mi-interp.c @@ -72,15 +72,6 @@ display_mi_prompt (struct mi_interp *mi) ui->prompt_state = PROMPTED; } -/* Returns the INTERP's data cast as mi_interp if INTERP is an MI, and - returns NULL otherwise. */ - -static struct mi_interp * -as_mi_interp (struct interp *interp) -{ - return dynamic_cast (interp); -} - void mi_interp::on_command_error () { diff --git a/gdb/mi/mi-interp.h b/gdb/mi/mi-interp.h index ce003242801..6326ec7d524 100644 --- a/gdb/mi/mi-interp.h +++ b/gdb/mi/mi-interp.h @@ -107,4 +107,13 @@ public: void mi_output_solib_attribs (ui_out *uiout, struct so_list *solib); +/* Returns the INTERP's data cast as mi_interp if INTERP is an MI, and + returns NULL otherwise. */ + +static inline struct mi_interp * +as_mi_interp (struct interp *interp) +{ + return dynamic_cast (interp); +} + #endif /* MI_MI_INTERP_H */ diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c index 9108cf505c7..0ac2c74153d 100644 --- a/gdb/mi/mi-main.c +++ b/gdb/mi/mi-main.c @@ -144,14 +144,21 @@ static void print_diff (struct ui_file *file, struct mi_timestamp *start, void mi_cmd_gdb_exit (const char *command, const char *const *argv, int argc) { - struct mi_interp *mi = (struct mi_interp *) current_interpreter (); - - /* We have to print everything right here because we never return. */ - if (current_token) - gdb_puts (current_token, mi->raw_stdout); - gdb_puts ("^exit\n", mi->raw_stdout); - mi_out_put (current_uiout, mi->raw_stdout); - gdb_flush (mi->raw_stdout); + struct mi_interp *mi = as_mi_interp (current_interpreter ()); + + /* If the current interpreter is not an MI interpreter, then just + don't bother printing anything. This case can arise from using + the Python gdb.execute_mi function -- but here the result does + not matter, as gdb is about to exit anyway. */ + if (mi != nullptr) + { + /* We have to print everything right here because we never return. */ + if (current_token) + gdb_puts (current_token, mi->raw_stdout); + gdb_puts ("^exit\n", mi->raw_stdout); + mi_out_put (current_uiout, mi->raw_stdout); + gdb_flush (mi->raw_stdout); + } /* FIXME: The function called is not yet a formal libgdb function. */ quit_force (NULL, FROM_TTY); } @@ -1802,10 +1809,9 @@ mi_cmd_remove_inferior (const char *command, const char *const *argv, int argc) prompt, display error). */ static void -captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context) +captured_mi_execute_command (struct mi_interp *mi, struct ui_out *uiout, + struct mi_parse *context) { - struct mi_interp *mi = (struct mi_interp *) command_interp (); - if (do_timings) current_command_ts = context->cmd_start; @@ -1891,10 +1897,9 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context) /* Print a gdb exception to the MI output stream. */ static void -mi_print_exception (const char *token, const struct gdb_exception &exception) +mi_print_exception (struct mi_interp *mi, const char *token, + const struct gdb_exception &exception) { - struct mi_interp *mi = (struct mi_interp *) current_interpreter (); - gdb_puts (token, mi->raw_stdout); gdb_puts ("^error,msg=\"", mi->raw_stdout); if (exception.message == NULL) @@ -1926,13 +1931,15 @@ mi_execute_command (const char *cmd, int from_tty) target_log_command (cmd); + struct mi_interp *mi + = gdb::checked_static_cast (command_interp ()); try { command = mi_parse::make (cmd, &token); } catch (const gdb_exception &exception) { - mi_print_exception (token.c_str (), exception); + mi_print_exception (mi, token.c_str (), exception); } if (command != NULL) @@ -1947,7 +1954,7 @@ mi_execute_command (const char *cmd, int from_tty) try { - captured_mi_execute_command (current_uiout, command.get ()); + captured_mi_execute_command (mi, current_uiout, command.get ()); } catch (const gdb_exception &result) { @@ -1960,7 +1967,7 @@ mi_execute_command (const char *cmd, int from_tty) /* The command execution failed and error() was called somewhere. */ - mi_print_exception (command->token.c_str (), result); + mi_print_exception (mi, command->token.c_str (), result); mi_out_rewind (current_uiout); /* Throw to a higher level catch for SIGTERM sent to GDB. */ @@ -2189,7 +2196,12 @@ mi_load_progress (const char *section_name, static steady_clock::time_point last_update; static char *previous_sect_name = NULL; int new_section; - struct mi_interp *mi = (struct mi_interp *) current_interpreter (); + struct mi_interp *mi = as_mi_interp (current_interpreter ()); + + /* If the current interpreter is not an MI interpreter, then just + don't bother printing anything. */ + if (mi == nullptr) + return; /* This function is called through deprecated_show_load_progress which means uiout may not be correct. Fix it for the duration -- 2.30.2