1 files changed, 80 insertions, 0 deletions
diff --git a/debian/patches/73_04-Fix-host_name_lookup-Close-2747.patch b/debian/patches/73_04-Fix-host_name_lookup-Close-2747.patch
new file mode 100644
index 0000000..dd5c982
--- /dev/null
+++ b/debian/patches/73_04-Fix-host_name_lookup-Close-2747.patch
@@ -0,0 +1,80 @@
+From 20812729e3e47a193a21d326ecd036d67a8b2724 Mon Sep 17 00:00:00 2001
+From: "Heiko Schlittermann (HS12-RIPE)" <hs@schlittermann.de>
+Date: Sun, 16 May 2021 19:11:19 +0200
+Subject: [PATCH 4/4] Fix host_name_lookup (Close 2747)
+
+Thanks to Nico R for providing a reproducing configuration.
+
+        host_lookup             = *
+        message_size_limit      = ${if def:sender_host_name {32M}{32M}}
+        acl_smtp_connect        = acl_smtp_connect
+        acl_smtp_rcpt           = acl_smtp_rcpt
+
+        begin acl
+          acl_smtp_connect:
+                warn ratelimit = 256 / 1m / per_conn
+                accept
+
+          acl_smtp_rcpt:
+                accept hosts = 127.0.0.*
+
+        begin routers
+        null:
+          driver          = accept
+          transport       = null
+
+        begin transports
+        null:
+          driver          = appendfile
+          file            = /dev/null
+
+Tested with
+
+        swaks -f mailbox@example.org -t mailbox@example.org --pipe 'exim -bh 127.0.0.1 -C /opt/exim/etc/exim-bug.conf'
+
+The IP must have a PTR to "localhost." to reproduce it.
+---
+ src/host.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/host.c b/src/host.c
+index ee9d323a7..2047b9798 100644
+--- a/src/host.c
++++ b/src/host.c
+@@ -1577,15 +1577,15 @@ Put it in permanent memory. */
+ 
+   sender_host_name = string_copylc(US hosts->h_name);
+ 
+   /* If the host has aliases, build a copy of the alias list */
+ 
+   if (hosts->h_aliases)
+     {
+-    int count = 1;
++    int count = 1;  /* need 1 more for terminating NULL */
+     uschar **ptr;
+ 
+     for (uschar ** aliases = USS hosts->h_aliases; *aliases; aliases++) count++;
+     store_pool = POOL_PERM;
+     ptr = sender_host_aliases = store_get(count * sizeof(uschar *), FALSE);
+     store_pool = POOL_TAINT_PERM;
+ 
+@@ -1686,15 +1686,15 @@ while ((ordername = string_nextinlist(&list, &sep, NULL, 0)))
+     if failure. (PTR records that yield empty names have been encountered in
+     the DNS.) */
+ 
+     if (rc == DNS_SUCCEED)
+       {
+       uschar **aptr = NULL;
+       int ssize = 264;
+-      int count = 0;
++      int count = 1;  /* need 1 more for terminating NULL */
+       int old_pool = store_pool;
+ 
+       sender_host_dnssec = dns_is_secure(dnsa);
+       DEBUG(D_dns)
+         debug_printf("Reverse DNS security status: %s\n",
+             sender_host_dnssec ? "DNSSEC verified (AD)" : "unverified");
+ 
+-- 
+2.30.2
+