autofs-5.1.4 - fix use after free in do_master_list_reset()

From: Ian Kent <raven@themaw.net>

Umm ... list_for_each() can't be used in do_master_list_reset() because
the subject entry of the loop is removed for the list within the loop
body. Therefore it can't be used to calculate the next pointer within a
for (...) loop.

There is no list_for_each_safe() macro in the list.h of autofs so it
needs to be done manually.

Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG          |    1 +
 daemon/automount.c |    8 ++++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 4cb23f2..6cd3029 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -289,6 +289,7 @@
 - fix open calls not using open_xxxx() calls.
 - move open_xxxx() functions to spawn.c.
 - serialize calls to open_xxxx() functions.
+- fix use after free in do_master_list_reset().
 
 25/07/2012 autofs-5.0.7
 =======================
diff --git a/daemon/automount.c b/daemon/automount.c
index d96cd35..1a61b90 100644
--- a/daemon/automount.c
+++ b/daemon/automount.c
@@ -2075,14 +2075,18 @@ static void remove_empty_args(char **argv, int *argc)
 
 static void do_master_list_reset(struct master *master)
 {
-	struct list_head *head, *p;
+	struct list_head *head, *p, *n;
 
 	master_mutex_lock();
 
 	head = &master->mounts;
-	list_for_each(p, head) {
+	n = head->next;
+	while (n != head) {
 		struct master_mapent *entry;
 
+		p = n;
+		n = p->next;
+
 		entry = list_entry(p, struct master_mapent, list);
 
 		if (!list_empty(&entry->list))