[PATCH for-4.19 v2] tools/xl: Open xldevd.log with O_CLOEXEC

[Andrew Cooper <andrew.cooper3@citrix.com>]

`xl devd` has been observed leaking /var/log/xldevd.log into children.

Note this is specifically safe; dup2() leaves O_CLOEXEC disabled on newfd, so
after setting up stdout/stderr, it's only the logfile fd which will close on
exec().

Link: https://github.com/QubesOS/qubes-issues/issues/8292
Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Anthony PERARD <anthony@xenproject.org>
CC: Juergen Gross <jgross@suse.com>
CC: Demi Marie Obenour <demi@invisiblethingslab.com>
CC: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
CC: Oleksii Kurochko <oleksii.kurochko@gmail.com>

Also entirely speculative based on the QubesOS ticket.

v2:
 * Extend the commit message to explain why stdout/stderr aren't closed by
   this change

For 4.19.  This bugfix was posted earlier, but fell between the cracks.
---
 tools/xl/xl_utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/xl/xl_utils.c b/tools/xl/xl_utils.c
index 17489d182954..060186db3a59 100644
--- a/tools/xl/xl_utils.c
+++ b/tools/xl/xl_utils.c
@@ -270,7 +270,7 @@ int do_daemonize(const char *name, const char *pidfile)
         exit(-1);
     }
 
-    CHK_SYSCALL(logfile = open(fullname, O_WRONLY|O_CREAT|O_APPEND, 0644));
+    CHK_SYSCALL(logfile = open(fullname, O_WRONLY | O_CREAT | O_APPEND | O_CLOEXEC, 0644));
     free(fullname);
     assert(logfile >= 3);
 
-- 
2.39.2