From: Florian Forster <octo@collectd.org>
Date: Wed, 17 Jun 2015 08:37:31 +0000 (+0200)
Subject: email plugin: Fix freeing linked lists.
X-Git-Tag: collectd-5.5.1~105^2~5
X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=1205b167f300adacdcf7d5dd385299d2b05ace32;p=collectd.git

email plugin: Fix freeing linked lists.

The previous code essentially did:

    for (…; …; ptr = ptr->next)
      free (ptr);

The "ptr->next" is a use-after-free.
---

diff --git a/src/email.c b/src/email.c
index 8f633cd1..4aac3e31 100644
--- a/src/email.c
+++ b/src/email.c
@@ -570,10 +570,27 @@ static int email_init (void)
 	return (0);
 } /* int email_init */
 
-static int email_shutdown (void)
+static void type_list_free (type_list_t *t)
 {
-	type_t *ptr = NULL;
+	type_t *this;
+
+	this = t->head;
+	while (this != NULL)
+	{
+		type_t *next = this->next;
+
+		sfree (this->name);
+		sfree (this);
+
+		this = next;
+	}
 
+	t->head = NULL;
+	t->tail = NULL;
+}
+
+static int email_shutdown (void)
+{
 	int i = 0;
 
 	if (connector != ((pthread_t) 0)) {
@@ -613,35 +630,12 @@ static int email_shutdown (void)
 
 	pthread_mutex_unlock (&conns_mutex);
 
-	for (ptr = list_count.head; NULL != ptr; ptr = ptr->next) {
-		free (ptr->name);
-		free (ptr);
-	}
-
-	for (ptr = list_count_copy.head; NULL != ptr; ptr = ptr->next) {
-		free (ptr->name);
-		free (ptr);
-	}
-
-	for (ptr = list_size.head; NULL != ptr; ptr = ptr->next) {
-		free (ptr->name);
-		free (ptr);
-	}
-
-	for (ptr = list_size_copy.head; NULL != ptr; ptr = ptr->next) {
-		free (ptr->name);
-		free (ptr);
-	}
-
-	for (ptr = list_check.head; NULL != ptr; ptr = ptr->next) {
-		free (ptr->name);
-		free (ptr);
-	}
-
-	for (ptr = list_check_copy.head; NULL != ptr; ptr = ptr->next) {
-		free (ptr->name);
-		free (ptr);
-	}
+	type_list_free (&list_count);
+	type_list_free (&list_count_copy);
+	type_list_free (&list_size);
+	type_list_free (&list_size_copy);
+	type_list_free (&list_check);
+	type_list_free (&list_check_copy);
 
 	unlink ((NULL == sock_file) ? SOCK_PATH : sock_file);