From: Todd C. Miller <Todd.Miller@courtesan.com>
Date: Tue, 10 Apr 2012 14:18:39 +0000 (-0400)
Subject: Linux select() may return ENOMEM if there is a kernel resource
X-Git-Tag: SUDO_1_8_5~1^2~67
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=df04ccb207bd79365d7b1a26f3eb2ad6785f8875;p=sudo

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 285176009..1aa41ae54 100644
--- 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 dd14f8ad5..51733f63a 100644
--- 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);