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init: do not run shutdown/reexec actions from signal handler

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this is racy wrt various libc functions such as syslog()

function                                             old     new   delta
check_delayed_sigs                                   182     352    +170
init_main                                            772     728     -44
restart_handler                                       74       -     -74
halt_reboot_pwoff                                     79       -     -79
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 1/1 up/down: 170/-197)          Total: -27 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2014-11-21 20:10:57 +01:00
parent 4e314faa0a
commit 2bba9ad67a
1 changed files with 30 additions and 20 deletions
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50
init/init.c
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@ -822,7 +822,7 @@ static void halt_reboot_pwoff(int sig)
/* Handler for QUIT - exec "restart" action,
* else (no such action defined) do nothing */
static void restart_handler(int sig UNUSED_PARAM)
static void exec_restart_action(void)
{
struct init_action *a;
@ -975,6 +975,20 @@ static int check_delayed_sigs(void)
#endif
if (sig == SIGINT)
run_actions(CTRLALTDEL);
if (sig == SIGQUIT) {
exec_restart_action();
/* returns only if no restart action defined */
}
if ((1 << sig) & (0
#ifdef SIGPWR
+ (1 << SIGPWR)
#endif
+ (1 << SIGUSR1)
+ (1 << SIGUSR2)
+ (1 << SIGTERM)
)) {
halt_reboot_pwoff(sig);
}
}
}
@ -1070,7 +1084,7 @@ int init_main(int argc UNUSED_PARAM, char **argv)
#if 0
/* It's 2013, does anyone really still depend on this? */
/* If you do, consider adding swapon to sysinot actions then! */
/* If you do, consider adding swapon to sysinit actions then! */
/* struct sysinfo is linux-specific */
# ifdef __linux__
/* Make sure there is enough memory to do something useful. */
@ -1134,16 +1148,6 @@ int init_main(int argc UNUSED_PARAM, char **argv)
if (!DEBUG_INIT) {
struct sigaction sa;
bb_signals(0
#ifdef SIGPWR
+ (1 << SIGPWR) /* halt */
#endif
+ (1 << SIGUSR1) /* halt */
+ (1 << SIGTERM) /* reboot */
+ (1 << SIGUSR2) /* poweroff */
, halt_reboot_pwoff);
signal(SIGQUIT, restart_handler); /* re-exec another init */
/* Stop handler must allow only SIGCONT inside itself */
memset(&sa, 0, sizeof(sa));
sigfillset(&sa.sa_mask);
@ -1158,18 +1162,24 @@ int init_main(int argc UNUSED_PARAM, char **argv)
*/
sigaction_set(SIGSTOP, &sa); /* pause */
/* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
/* These signals must interrupt wait(),
* setting handler without SA_RESTART flag.
*/
bb_signals_recursive_norestart((1 << SIGINT), record_signo);
bb_signals_recursive_norestart(0
+ (1 << SIGINT) /* Ctrl-Alt-Del */
+ (1 << SIGQUIT) /* re-exec another init */
#ifdef SIGPWR
+ (1 << SIGPWR) /* halt */
#endif
+ (1 << SIGUSR1) /* halt */
+ (1 << SIGTERM) /* reboot */
+ (1 << SIGUSR2) /* poweroff */
#if ENABLE_FEATURE_USE_INITTAB
+ (1 << SIGHUP) /* reread /etc/inittab */
#endif
, record_signo);
}
/* Set up "reread /etc/inittab" handler.
* Handler is set up without SA_RESTART, it will interrupt syscalls.
*/
if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
/* Now run everything that needs to be run */
/* First run the sysinit command */
run_actions(SYSINIT);