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Initialize exec closure before calling sudo_fatal_callback_register()
The pty_cleanup() function, which may be called via fatal()/fatalx(), expects that ec->details is set. If there is a fatal error after the cleanup hook is registered but before the exec closure it filled in, pty_cleanup() would dereference a NULL pointer. Reported by Bjorn Baron.
This commit is contained in:
Todd C. Miller
parent
6fc816d90b
commit
0be9f0f947
135
src/exec_pty.c
135
src/exec_pty.c
@ -1,7 +1,7 @@
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/*
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* SPDX-License-Identifier: ISC
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*
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* Copyright (c) 2009-2024 Todd C. Miller <Todd.Miller@sudo.ws>
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* Copyright (c) 2009-2025 Todd C. Miller <Todd.Miller@sudo.ws>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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@ -63,44 +63,6 @@ static void sync_ttysize(struct exec_closure *ec);
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static void schedule_signal(struct exec_closure *ec, int signo);
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static void send_command_status(struct exec_closure *ec, int type, int val);
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/*
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* Allocate a pty if /dev/tty is a tty.
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* Fills in io_fds[SFD_USERTTY], io_fds[SFD_LEADER] and io_fds[SFD_FOLLOWER].
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* Returns the dynamically allocated pty name on success, NULL on failure.
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*/
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static char *
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pty_setup(struct command_details *details)
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{
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char *ptyname = NULL;
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debug_decl(pty_setup, SUDO_DEBUG_EXEC);
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io_fds[SFD_USERTTY] = open(_PATH_TTY, O_RDWR);
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if (io_fds[SFD_USERTTY] == -1) {
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sudo_debug_printf(SUDO_DEBUG_INFO, "%s: no %s, not allocating a pty",
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__func__, _PATH_TTY);
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debug_return_ptr(NULL);
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}
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ptyname = get_pty(&io_fds[SFD_LEADER], &io_fds[SFD_FOLLOWER],
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details->cred.euid);
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if (ptyname == NULL)
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sudo_fatal("%s", U_("unable to allocate pty"));
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/* Add entry to utmp/utmpx? */
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if (ISSET(details->flags, CD_SET_UTMP))
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utmp_login(details->tty, ptyname, io_fds[SFD_FOLLOWER], details->utmp_user);
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/* Update tty name in command details (used by monitor, SELinux, AIX). */
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details->tty = ptyname;
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sudo_debug_printf(SUDO_DEBUG_INFO,
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"%s: %s fd %d, pty leader fd %d, pty follower fd %d",
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__func__, _PATH_TTY, io_fds[SFD_USERTTY], io_fds[SFD_LEADER],
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io_fds[SFD_FOLLOWER]);
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debug_return_str(ptyname);
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}
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/*
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* Restore user's terminal settings and update utmp, as needed.
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*/
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@ -136,6 +98,49 @@ pty_cleanup_hook(void)
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pty_cleanup(&pty_ec, 0);
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}
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/*
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* Allocate a pty if /dev/tty is a tty.
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* Fills in io_fds[SFD_USERTTY], io_fds[SFD_LEADER] and io_fds[SFD_FOLLOWER].
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* Returns the dynamically allocated pty name on success, NULL on failure.
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*/
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static bool
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pty_setup(struct exec_closure *ec)
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{
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struct command_details *details = ec->details;
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debug_decl(pty_setup, SUDO_DEBUG_EXEC);
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io_fds[SFD_USERTTY] = open(_PATH_TTY, O_RDWR);
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if (io_fds[SFD_USERTTY] == -1) {
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sudo_debug_printf(SUDO_DEBUG_INFO, "%s: no %s, not allocating a pty",
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__func__, _PATH_TTY);
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debug_return_bool(false);
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}
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ec->ptyname = get_pty(&io_fds[SFD_LEADER], &io_fds[SFD_FOLLOWER],
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details->cred.euid);
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if (ec->ptyname == NULL)
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sudo_fatal("%s", U_("unable to allocate pty"));
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/* Add entry to utmp/utmpx? */
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if (ISSET(details->flags, CD_SET_UTMP)) {
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utmp_login(details->tty, ec->ptyname, io_fds[SFD_FOLLOWER],
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details->utmp_user);
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}
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/* Update tty name in command details (used by monitor, SELinux, AIX). */
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details->tty = ec->ptyname;
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/* Register cleanup function. */
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sudo_fatal_callback_register(pty_cleanup_hook);
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sudo_debug_printf(SUDO_DEBUG_INFO,
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"%s: %s fd %d, pty leader fd %d, pty follower fd %d",
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__func__, _PATH_TTY, io_fds[SFD_USERTTY], io_fds[SFD_LEADER],
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io_fds[SFD_FOLLOWER]);
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debug_return_bool(true);
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}
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/*
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* Check whether sudo is running in the foreground.
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* Updates the foreground flag in the closure.
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@ -956,16 +961,14 @@ fwdchannel_cb(int sock, int what, void *v)
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}
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/*
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* Fill in the exec closure and setup initial exec events.
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* Allocates events for the signal pipe and backchannel.
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* Forwarded signals on the backchannel are enabled on demand.
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* Fill in the non-event part of the exec closure.
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*/
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static void
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fill_exec_closure(struct exec_closure *ec, struct command_status *cstat,
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init_exec_closure(struct exec_closure *ec, struct command_status *cstat,
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struct command_details *details, const struct user_details *user_details,
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struct sudo_event_base *evbase, pid_t sudo_pid, pid_t ppgrp, int backchannel)
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pid_t sudo_pid, pid_t ppgrp)
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{
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debug_decl(fill_exec_closure, SUDO_DEBUG_EXEC);
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debug_decl(init_exec_closure, SUDO_DEBUG_EXEC);
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/* Fill in the non-event part of the closure. */
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ec->sudo_pid = sudo_pid;
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@ -976,9 +979,18 @@ fill_exec_closure(struct exec_closure *ec, struct command_status *cstat,
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ec->rows = user_details->ts_rows;
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ec->cols = user_details->ts_cols;
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/* Reset cstat for running the command. */
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cstat->type = CMD_INVALID;
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cstat->val = 0;
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debug_return;
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}
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/*
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* Allocate and set events for the signal pipe and backchannel.
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* Forwarded signals on the backchannel are enabled on demand.
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*/
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static void
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init_exec_events(struct exec_closure *ec, struct sudo_event_base *evbase,
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int backchannel)
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{
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debug_decl(init_exec_events, SUDO_DEBUG_EXEC);
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/* Setup event base and events. */
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ec->evbase = evbase;
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@ -1099,23 +1111,22 @@ exec_pty(struct command_details *details,
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int sv[2], intercept_sv[2] = { -1, -1 };
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struct exec_closure *ec = &pty_ec;
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struct plugin_container *plugin;
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const pid_t sudo_pid = getpid();
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const pid_t ppgrp = getpgrp();
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int evloop_retries = -1;
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bool cmnd_foreground;
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sigset_t set, oset;
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struct sigaction sa;
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pid_t ppgrp, sudo_pid;
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debug_decl(exec_pty, SUDO_DEBUG_EXEC);
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/*
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* Allocate a pty if sudo is running in a terminal.
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* Allocate a pty if sudo is running in a terminal. The exec
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* closure must be set for pty_setup() and pty_cleanup_hook().
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*/
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ec->ptyname = pty_setup(details);
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if (ec->ptyname == NULL)
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init_exec_closure(ec, cstat, details, user_details, sudo_pid, ppgrp);
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if (!pty_setup(ec))
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debug_return_bool(false);
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/* Register cleanup function */
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sudo_fatal_callback_register(pty_cleanup_hook);
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/*
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* We communicate with the monitor over a bi-directional pair of sockets.
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* Parent sends signal info to monitor and monitor sends back wait status.
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@ -1161,8 +1172,6 @@ exec_pty(struct command_details *details,
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* to and from pty.
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*/
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init_ttyblock();
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ppgrp = getpgrp(); /* parent's pgrp, so child can signal us */
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sudo_pid = getpid();
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/* Determine whether any of std{in,out,err} should be logged. */
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TAILQ_FOREACH(plugin, &io_plugins, entries) {
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@ -1400,12 +1409,8 @@ exec_pty(struct command_details *details,
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if (ISSET(details->flags, CD_SET_TIMEOUT))
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alarm(details->timeout);
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/*
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* Fill in exec closure, allocate event base, signal events and
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* the backchannel event.
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*/
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fill_exec_closure(ec, cstat, details, user_details, evbase,
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sudo_pid, ppgrp, sv[0]);
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/* Allocate and set signal events and the backchannel event. */
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init_exec_events(ec, evbase, sv[0]);
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/* Create event and closure for intercept mode. */
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if (ISSET(details->flags, CD_INTERCEPT|CD_LOG_SUBCMDS)) {
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@ -1414,6 +1419,10 @@ exec_pty(struct command_details *details,
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terminate_command(ec->cmnd_pid, true);
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}
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/* Reset cstat for running the command. */
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cstat->type = CMD_INVALID;
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cstat->val = 0;
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/* Restore signal mask now that signal handlers are setup. */
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sigprocmask(SIG_SETMASK, &oset, NULL);
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