vlog: Avoid use-after-free in corner case.

Found by valgrind.

Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/lib/vlog.c b/lib/vlog.c
index a7d9e48b9ddd9d7fef59c7854b946191f28910b8..899072e451e58d934a2aef628686a69397d266b2 100644 (file)
--- a/lib/vlog.c
+++ b/lib/vlog.c
@@ -477,6 +477,7 @@ vlog_unixctl_reopen(struct unixctl_conn *conn, int argc OVS_UNUSED,
 void
 vlog_init(void)
 {
+    static char *program_name_copy;
     time_t now;
 
     if (vlog_inited) {
@@ -484,7 +485,13 @@ vlog_init(void)
     }
     vlog_inited = true;
 
-    openlog(program_name, LOG_NDELAY, LOG_DAEMON);
+    /* openlog() is allowed to keep the pointer passed in, without making a
+     * copy.  The daemonize code sometimes frees and replaces 'program_name',
+     * so make a private copy just for openlog().  (We keep a pointer to the
+     * private copy to suppress memory leak warnings in case openlog() does
+     * make its own copy.) */
+    program_name_copy = program_name ? xstrdup(program_name) : NULL;
+    openlog(program_name_copy, LOG_NDELAY, LOG_DAEMON);
 
     now = time_wall();
     if (now < 0) {