From: Lennart Poettering <lennart@poettering.net>
Date: Sat, 23 Dec 2017 23:54:40 +0000 (+0100)
Subject: terminal-util: open /dev/null with O_CLOEXEC in make_stdio_null()
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=7cfc65cbfb5fb2e06710cab0d5008a0643735d49;p=elogind.git

terminal-util: open /dev/null with O_CLOEXEC in make_stdio_null()

Ultimately, O_CLOEXEC should be off in fd 0, 1, 2, but when we open
/dev/null here it's unlikely to be < 0, and after dupping the fd to 0,
1, 2 we turn off O_CLOEXEC explicitly anyway.

Unless we know that what we are about to open will return 0, 1 or 2 we
should always set O_CLOEXEC in order to be safe to other threads forking
of subprocesses at the wrong moment.
---

diff --git a/src/basic/terminal-util.c b/src/basic/terminal-util.c
index 3ece0697f..c67b34073 100644
--- a/src/basic/terminal-util.c
+++ b/src/basic/terminal-util.c
@@ -910,7 +910,7 @@ int make_stdio(int fd) {
 int make_null_stdio(void) {
         int null_fd;
 
-        null_fd = open("/dev/null", O_RDWR|O_NOCTTY);
+        null_fd = open("/dev/null", O_RDWR|O_NOCTTY|O_CLOEXEC);
         if (null_fd < 0)
                 return -errno;