log: never log into foreign fd #2 in PID 1 or its pre-execve() children

Fixes: #5401

1 files changed, 9 insertions, 2 deletions

diff --git a/src/core/main.c b/src/core/main.c
index 3c6b18229c..bcf9ea5f25 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -1414,10 +1414,17 @@ int main(int argc, char *argv[]) {
 
         log_set_upgrade_syslog_to_journal(true);
 
-        /* Disable the umask logic */
-        if (getpid() == 1)
+        if (getpid() == 1) {
+                /* Disable the umask logic */
                 umask(0);
 
+                /* Always reopen /dev/console when running as PID 1 or one of its pre-execve() children. This is
+                 * important so that we never end up logging to any foreign stderr, for example if we have to log in a
+                 * child process right before execve()'ing the actual binary, at a point in time where socket
+                 * activation stderr/stdout area already set up. */
+                log_set_always_reopen_console(true);
+        }
+
         if (getpid() == 1 && detect_container() <= 0) {
 
                 /* Running outside of a container as PID 1 */