instance: fix pidfile and seccomp attributes double free
authorPetr Štetiar <ynezz@true.cz>
Fri, 17 Jan 2020 17:22:37 +0000 (18:22 +0100)
committerDaniel Golle <daniel@makrotopia.org>
Sat, 18 Jan 2020 09:14:42 +0000 (11:14 +0200)
Commit a5af33ce9a16 ("instance: strdup string attributes") has
introduced duplication of various string attributes in order to fix
use-after-free, but missed handling of `pidfile` and `seccomp` attribute
cases in instance_config_move() where the new value of `pidfile` or
`seccomp` is being copied/assigned. Source of this values is then
free()d in subsequent call to instance_free() and then again for 2nd
time during the service stop command handling, leading to double free
crash:

 #0  unmap_chunk at src/malloc/malloc.c:515
 #1  free at src/malloc/malloc.c:526
 #2  instance_free (in=0xd5e300) at instance.c:1100
 #3  instance_delete (in=0xd5e300) at instance.c:559
 #4  instance_stop (in=0xd5e300, halt=true) at instance.c:611

While at it, add missing handling of jail.name and jail.hostname
attributes as well.

Ref: FS#2723
Fixes: a5af33ce9a16 ("instance: strdup string attributes")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Petr Štetiar <ynezz@true.cz>
service/instance.c

index b0c9807..342199a 100644 (file)
@@ -1018,6 +1018,21 @@ instance_config_cleanup(struct service_instance *in)
        blobmsg_list_free(&in->jail.mount);
 }
 
+static void
+instance_config_move_strdup(char **dst, char *src)
+{
+       if (!*dst)
+               return;
+
+       free(*dst);
+       *dst = NULL;
+
+       if (!src)
+               return;
+
+       *dst = strdup(src);
+}
+
 static void
 instance_config_move(struct service_instance *in, struct service_instance *in_src)
 {
@@ -1031,17 +1046,20 @@ instance_config_move(struct service_instance *in, struct service_instance *in_sr
        blobmsg_list_move(&in->jail.mount, &in_src->jail.mount);
        in->trigger = in_src->trigger;
        in->command = in_src->command;
-       in->pidfile = in_src->pidfile;
        in->respawn = in_src->respawn;
        in->respawn_retry = in_src->respawn_retry;
        in->respawn_threshold = in_src->respawn_threshold;
        in->respawn_timeout = in_src->respawn_timeout;
        in->name = in_src->name;
        in->trace = in_src->trace;
-       in->seccomp = in_src->seccomp;
        in->node.avl.key = in_src->node.avl.key;
        in->syslog_facility = in_src->syslog_facility;
 
+       instance_config_move_strdup(&in->pidfile, in_src->pidfile);
+       instance_config_move_strdup(&in->seccomp, in_src->seccomp);
+       instance_config_move_strdup(&in->jail.name, in_src->jail.name);
+       instance_config_move_strdup(&in->jail.hostname, in_src->jail.hostname);
+
        free(in->config);
        in->config = in_src->config;
        in_src->config = NULL;