Fix several memory leaks.

The libkqueue tests have several places that leak memory by using an
idiom like:

puts(kevent_to_str(kevp));

Rework to save the pointer returned from kevent_to_str() and then
free() it after it has been used.

Reported by:	asomers (pointer to Coverity), Coverity
CID:		1296063, 1296064, 1296065, 1296066, 1296067, 1350287, 1394960
Sponsored by:	Dell EMC

4 files changed, 22 insertions, 8 deletions

diff --git a/sys/dev/netmap/netmap_freebsd.c b/sys/dev/netmap/netmap_freebsd.c
index f4a97b370f68..b2882768297b 100644
--- a/sys/dev/netmap/netmap_freebsd.c
+++ b/sys/dev/netmap/netmap_freebsd.c
@@ -1498,7 +1498,7 @@ netmap_kqfilter(struct cdev *dev, struct knote *kn)
 	kn->kn_fop = (ev == EVFILT_WRITE) ?
 		&netmap_wfiltops : &netmap_rfiltops;
 	kn->kn_hook = priv;
-	knlist_add(&si->si.si_note, kn, 1);
+	knlist_add(&si->si.si_note, kn, 0);
 	// XXX unlock(priv)
 	ND("register %p %s td %p priv %p kn %p np_nifp %p kn_fp/fpop %s",
 		na, na->ifp->if_xname, curthread, priv, kn,
diff --git a/tests/sys/kqueue/libkqueue/common.h b/tests/sys/kqueue/libkqueue/common.h
index 46f6f54d81dd..814d6cc0fc93 100644
--- a/tests/sys/kqueue/libkqueue/common.h
+++ b/tests/sys/kqueue/libkqueue/common.h
@@ -43,7 +43,7 @@
 extern char *cur_test_id;
 int vnode_fd;
 
-extern const char * kevent_to_str(struct kevent *);
+extern char * kevent_to_str(struct kevent *);
 struct kevent * kevent_get(int);
 struct kevent * kevent_get_timeout(int, int);
 
diff --git a/tests/sys/kqueue/libkqueue/main.c b/tests/sys/kqueue/libkqueue/main.c
index 616eb8ddd696..9b8945e3f2b9 100644
--- a/tests/sys/kqueue/libkqueue/main.c
+++ b/tests/sys/kqueue/libkqueue/main.c
@@ -41,13 +41,16 @@ test_no_kevents(void)
     int nfds;
     struct timespec timeo;
     struct kevent kev;
+    char *kev_str;
 
     puts("confirming that there are no events pending");
     memset(&timeo, 0, sizeof(timeo));
     nfds = kevent(kqfd, NULL, 0, &kev, 1, &timeo);
     if (nfds != 0) {
         puts("\nUnexpected event:");
-        puts(kevent_to_str(&kev));
+        kev_str = kevent_to_str(&kev);
+        puts(kev_str);
+        free(kev_str);
         errx(1, "%d event(s) pending, but none expected:", nfds);
     }
 }
@@ -61,12 +64,15 @@ test_no_kevents_quietly(void)
     int nfds;
     struct timespec timeo;
     struct kevent kev;
+    char *kev_str;
 
     memset(&timeo, 0, sizeof(timeo));
     nfds = kevent(kqfd, NULL, 0, &kev, 1, &timeo);
     if (nfds != 0) {
         puts("\nUnexpected event:");
-        puts(kevent_to_str(&kev));
+        kev_str = kevent_to_str(&kev);
+        puts(kev_str);
+        free(kev_str);
         errx(1, "%d event(s) pending, but none expected:", nfds);
     }
 }
@@ -193,18 +199,20 @@ kevent_flags_dump(struct kevent *kev)
 }
 
 /* Copied from ../kevent.c kevent_dump() and improved */
-const char *
+char *
 kevent_to_str(struct kevent *kev)
 {
     char buf[512];
+    char *flags_str = kevent_flags_dump(kev);
+    char *fflags_str = kevent_fflags_dump(kev);
 
     snprintf(&buf[0], sizeof(buf), 
             "[ident=%ju, filter=%d, %s, %s, data=%jd, udata=%p, "
 	    "ext=[%jx %jx %jx %jx]",
             (uintmax_t) kev->ident,
             kev->filter,
-            kevent_flags_dump(kev),
-            kevent_fflags_dump(kev),
+            flags_str,
+            fflags_str,
             (uintmax_t)kev->data,
             kev->udata,
 	    (uintmax_t)kev->ext[0],
@@ -212,6 +220,9 @@ kevent_to_str(struct kevent *kev)
 	    (uintmax_t)kev->ext[2],
 	    (uintmax_t)kev->ext[3]);
 
+    free(flags_str);
+    free(fflags_str);
+    
     return (strdup(buf));
 }
 
diff --git a/tests/sys/kqueue/libkqueue/proc.c b/tests/sys/kqueue/libkqueue/proc.c
index 79b8d35f4f25..4f97eacdc1a0 100644
--- a/tests/sys/kqueue/libkqueue/proc.c
+++ b/tests/sys/kqueue/libkqueue/proc.c
@@ -172,6 +172,7 @@ proc_track(int sleep_time)
         int gchild_note = 0;
         pid_t gchild_pid = -1;
         int done = 0;
+        char *kev_str;
         
         while (!done)
         {
@@ -182,7 +183,9 @@ proc_track(int sleep_time)
             if (kevp == NULL) {
                 done = 1;
             } else {
-                printf(" -- Received kevent: %s\n", kevent_to_str(kevp));
+                kev_str = kevent_to_str(kevp);
+                printf(" -- Received kevent: %s\n", kev_str);
+                free(kev_str);
             
                 if ((kevp->fflags & NOTE_CHILD) && (kevp->fflags & NOTE_EXIT)) {
                     errx(1, "NOTE_CHILD and NOTE_EXIT in same kevent: %s", kevent_to_str(kevp));