Re: [PATCH 1/2] mcstrans: defer SIGTERM cleanup to the main loop

On Thu, Jul 16, 2026 at 8:53 AM Stephen Smalley
<[email protected]> wrote:
>
> sigterm_handler() calls cleanup_exit(), which walks and frees the
> translation and color tables and unlinks the socket. None of that is
> async-signal-safe; a SIGTERM arriving while the main loop is inside
> malloc/free or inside finish_context_translations() during a SIGHUP
> reload can deadlock or corrupt the heap.
>
> Set a flag from the handler and let the top of the poll loop call
> cleanup_exit() from normal context, matching the existing SIGHUP
> restart_daemon pattern. poll() is not restarted (SA_RESTART is not
> set) so a signal delivered during the blocking poll returns EINTR and
> the loop rechecks the flag. The narrow check then poll window matches
> the existing SIGHUP handling.
>
> Signed-off-by: Stephen Smalley <[email protected]>

This series has been merged.

> ---
>  mcstrans/src/mcstransd.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/mcstrans/src/mcstransd.c b/mcstrans/src/mcstransd.c
> index 5bdaadb7..3db58a17 100644
> --- a/mcstrans/src/mcstransd.c
> +++ b/mcstrans/src/mcstransd.c
> @@ -58,6 +58,7 @@
>  static int sockfd = -1; /* socket we are listening on */
>
>  static volatile sig_atomic_t restart_daemon = false;
> +static volatile sig_atomic_t terminate = false;
>  static void cleanup_exit(int ret) __attribute__((noreturn));
>  static void cleanup_exit(int ret)
>  {
> @@ -407,6 +408,10 @@ static void process_connections(void)
>         ufds[0].revents = 0;
>
>         while (1) {
> +               if (terminate) {
> +                       free(ufds);
> +                       cleanup_exit(0);
> +               }
>                 if (restart_daemon) {
>                         syslog(LOG_NOTICE, "Reload Translations");
>                         finish_context_colors();
> @@ -442,11 +447,9 @@ static void process_connections(void)
>         }
>  }
>
> -static void sigterm_handler(int sig) __attribute__((noreturn));
> -
>  static void sigterm_handler(int UNUSED(sig))
>  {
> -       cleanup_exit(0);
> +       terminate = true;
>  }
>
>  static void sighup_handler(int UNUSED(sig))
> --
> 2.55.0
>