From 2f822da535ba9b159174d02d7114b4fc4f7c8818 Mon Sep 17 00:00:00 2001 From: Marco Barisione Date: Wed, 12 May 2021 11:19:22 +0100 Subject: gdb: generate the prefix name for prefix commands on demand Previously, the prefixname field of struct cmd_list_element was manually set for prefix commands. This seems verbose and error prone as it required every single call to functions adding prefix commands to specify the prefix name while the same information can be easily generated. Historically, this was not possible as the prefix field was null for many commands, but this was fixed in commit 3f4d92ebdf7f848b5ccc9e8d8e8514c64fde1183 by Philippe Waroquiers, so we can rely on the prefix field being set when generating the prefix name. This commit also fixes a use after free in this scenario: * A command gets created via Python (using the gdb.Command class). The prefix name member is dynamically allocated. * An alias to the new command is created. The alias's prefixname is set to point to the prefixname for the original command with a direct assignment. * A new command with the same name as the Python command is created. * The object for the original Python command gets freed and its prefixname gets freed as well. * The alias is updated to point to the new command, but its prefixname is not updated so it keeps pointing to the freed one. gdb/ChangeLog: * command.h (add_prefix_cmd): Remove the prefixname argument as it can now be generated automatically. Update all callers. (add_basic_prefix_cmd): Ditto. (add_show_prefix_cmd): Ditto. (add_prefix_cmd_suppress_notification): Ditto. (add_abbrev_prefix_cmd): Ditto. * cli/cli-decode.c (add_prefix_cmd): Ditto. (add_basic_prefix_cmd): Ditto. (add_show_prefix_cmd): Ditto. (add_prefix_cmd_suppress_notification): Ditto. (add_prefix_cmd_suppress_notification): Ditto. (add_abbrev_prefix_cmd): Ditto. * cli/cli-decode.h (struct cmd_list_element): Replace the prefixname member variable with a method which generates the prefix name at runtime. Update all code reading the prefix name to use the method, and remove all code setting it. * python/py-cmd.c (cmdpy_destroyer): Remove code to free the prefixname member as it's now a method. (cmdpy_function): Determine if the command is a prefix by looking at prefixlist, not prefixname. --- gdb/i386-tdep.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'gdb/i386-tdep.c') diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c index 50fd276..5e6769a 100644 --- a/gdb/i386-tdep.c +++ b/gdb/i386-tdep.c @@ -9031,14 +9031,14 @@ is \"default\"."), add_basic_prefix_cmd ("mpx", class_support, _("\ Set Intel Memory Protection Extensions specific variables."), - &mpx_set_cmdlist, "set mpx ", + &mpx_set_cmdlist, 0 /* allow-unknown */, &setlist); /* Add "mpx" prefix for the show commands. */ add_show_prefix_cmd ("mpx", class_support, _("\ Show Intel Memory Protection Extensions specific variables."), - &mpx_show_cmdlist, "show mpx ", + &mpx_show_cmdlist, 0 /* allow-unknown */, &showlist); /* Add "bound" command for the show mpx commands list. */ -- cgit v1.1