[exim-cvs] Fix unaligned access in DNS negative-caching

Gitweb: https://git.exim.org/exim.git/commitdiff/927e32d4e26593314c5c287b3033ed550d648706

Commit:     927e32d4e26593314c5c287b3033ed550d648706
Parent:     c3aefacc72991f4960486052775ab47cd83c5fae
Author:     Jeremy Harris <jgh146exb@???>
AuthorDate: Sun Sep 8 12:11:16 2019 +0100
Committer:  Jeremy Harris <jgh146exb@???>
CommitDate: Sun Sep 8 12:11:16 2019 +0100

    Fix unaligned access in DNS negative-caching
---
 src/src/dns.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/src/dns.c b/src/src/dns.c
index ece6524..04cb046 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -618,6 +618,12 @@ Returns:     the return code

/*XXX the derivation of this value needs explaining */
#define DNS_FAILTAG_MAX 290
+#define alignment \
+ (sizeof(void *) > sizeof(double) ? sizeof(void *) : sizeof(double))
+#define align(n) \
+ (((((intptr_t)n) + (alignment-1)) / alignment) * alignment)
+#define DNS_FAILNODE_SIZE \
+ align(sizeof(tree_node) + DNS_FAILTAG_MAX + sizeof(expiring_data))

 static int
 dns_fail_return(const uschar * name, int type, time_t expiry, int rc)
@@ -631,11 +637,10 @@ if ((previous = tree_search(tree_dns_fails, node_name)))
   e = previous->data.ptr;
 else
   {
-  new = store_get_perm(
-    sizeof(tree_node) + DNS_FAILTAG_MAX + sizeof(expiring_data), is_tainted(name));
+  new = store_get_perm(DNS_FAILNODE_SIZE, is_tainted(name));

dns_fail_tag(new->name, name, type);
- e = (expiring_data *)((char *)new + sizeof(tree_node) + DNS_FAILTAG_MAX);
+ e = (expiring_data *) align((char *)new + sizeof(tree_node) + DNS_FAILTAG_MAX);
new->data.ptr = e;
(void)tree_insertnode(&tree_dns_fails, new);
}