Linux select() may return ENOMEM if there is a kernel resource

shortage.  Older Solaris select() may return EIO instead of EBADF
when the tty goes away.  If we get an unhandled select() failure,
kill the child and exit cleanly.

diff --git a/src/exec.c b/src/exec.c
index 2851760095b36344548a9f1838e256c9de0c0bac..1aa41ae548b33fec3bc3b38338a12008369d12bc 100644 (file)
--- a/src/exec.c
+++ b/src/exec.c
@@ -335,13 +335,18 @@ sudo_execute(struct command_details *details, struct command_status *cstat)
        nready = select(maxfd + 1, fdsr, fdsw, NULL, NULL);
        sudo_debug_printf(SUDO_DEBUG_DEBUG, "select returns %d", nready);
        if (nready == -1) {
-           if (errno == EINTR)
+           if (errno == EINTR || errno == ENOMEM)
                continue;
-           if (errno == EBADF) {
+           if (errno == EBADF || errno == EIO) {
                /* One of the ttys must have gone away. */
                goto do_tty_io;
            }
-           error(1, _("select failed"));
+           warning(_("select failed"));
+           sudo_debug_printf(SUDO_DEBUG_ERROR,
+               "select failure, terminating child");
+           schedule_signal(SIGKILL);
+           forward_signals(sv[0]);
+           break;
        }
        if (FD_ISSET(sv[0], fdsw)) {
            forward_signals(sv[0]);

diff --git a/src/exec_pty.c b/src/exec_pty.c
index dd14f8ad58da0182f42052745bd625e56014b660..51733f63a5620c5cb5a22fdc7ccc73a87e1966e8 100644 (file)
--- a/src/exec_pty.c
+++ b/src/exec_pty.c
@@ -1015,9 +1015,10 @@ exec_monitor(struct command_details *details, int backchannel)
        if (n <= 0) {
            if (n == 0)
                goto done;
-           if (errno == EINTR)
+           if (errno == EINTR || errno == ENOMEM)
                continue;
-           error(1, "monitor: %s", _("select failed"));
+           warning("monitor: %s", _("select failed"));
+           break;
        }
 
        if (FD_ISSET(signal_pipe[0], fdsr)) {
@@ -1152,11 +1153,11 @@ flush_output(void)
        if (nready <= 0) {
            if (nready == 0)
                break; /* all I/O flushed */
-           if (errno == EINTR)
+           if (errno == EINTR || errno == ENOMEM)
                continue;
-           error(1, _("select failed"));
+           warning(_("select failed"));
        }
-       if (perform_io(fdsr, fdsw, NULL) != 0)
+       if (perform_io(fdsr, fdsw, NULL) != 0 || nready == -1)
            break;
     }
     efree(fdsr);