fix fdleak and errors in lxc_create_tty()

if, for some reason, openpty() fails, lxc_create_tty() will
leak all previous ptys and leave the config structure in a
inconsistent state (wrt the number of ptys actually opened)
Fix that by explicitly closing all previously opened ptys
in case of failure and by setting number of actually opened
ttys after actual open

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

1 files changed, 8 insertions, 13 deletions

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index abfdb60..9c3a558 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -995,29 +995,29 @@ int lxc_assign_network(struct lxc_list *network, pid_t pid)
 int lxc_create_tty(const char *name, struct lxc_conf *conf)
 {
 	struct lxc_tty_info *tty_info = &conf->tty_info;
-	int i, ret = -1;
+	int i;
 
 	/* no tty in the configuration */
 	if (!conf->tty)
 		return 0;
 
-	tty_info->nbtty = conf->tty;
 	tty_info->pty_info =
 		malloc(sizeof(*tty_info->pty_info)*tty_info->nbtty);
-
 	if (!tty_info->pty_info) {
 		SYSERROR("failed to allocate pty_info");
-		goto out;
+		return -1;
 	}
 
-	for (i = 0; i < tty_info->nbtty; i++) {
+	for (i = 0; i < conf->tty; i++) {
 
 		struct lxc_pty_info *pty_info = &tty_info->pty_info[i];
 
 		if (openpty(&pty_info->master, &pty_info->slave,
 			    pty_info->name, NULL, NULL)) {
 			SYSERROR("failed to create pty #%d", i);
-			goto out_free;
+			tty_info->nbtty = i;
+			lxc_delete_tty(tty_info);
+			return -1;
 		}
 
                 /* Prevent leaking the file descriptors to the container */
@@ -1027,16 +1027,11 @@ int lxc_create_tty(const char *name, struct lxc_conf *conf)
 		pty_info->busy = 0;
 	}
 
-	ret = 0;
+	tty_info->nbtty = conf->tty;
 
 	INFO("tty's configured");
 
-out:
-	return ret;
-
-out_free:
-	free(tty_info->pty_info);
-	goto out;
+	return 0;
 }
 
 void lxc_delete_tty(struct lxc_tty_info *tty_info)