X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/be24b950ae0db88b1c9811b3a028e95133c55efa..92583637b25b6bde926f9ca6be7b085e5ac8b1e6:/src/src/dkim.c

diff --git a/src/src/dkim.c b/src/src/dkim.c
index 17eb61603..87c9c9197 100644
--- a/src/src/dkim.c
+++ b/src/src/dkim.c
@@ -3,6 +3,7 @@
 *************************************************/
 
 /* Copyright (c) University of Cambridge, 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Code for DKIM support. Other DKIM relevant code is in
@@ -49,11 +50,14 @@ dkim_exim_query_dns_txt(const uschar * name)
 dns_answer * dnsa = store_get_dns_answer();
 dns_scan dnss;
 rmark reset_point = store_mark();
-gstring * g = NULL;
+gstring * g = string_get_tainted(256, TRUE);
 
 lookup_dnssec_authenticated = NULL;
 if (dns_lookup(dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
+  {
+  store_free_dns_answer(dnsa);
   return NULL;	/*XXX better error detail?  logging? */
+  }
 
 /* Search for TXT record */
 
@@ -80,6 +84,7 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
     /* check if this looks like a DKIM record */
     if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0)
       {
+      store_free_dns_answer(dnsa);
       gstring_release_unused(g);
       return string_from_gstring(g);
       }
@@ -89,6 +94,7 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
 
 bad:
 store_reset(reset_point);
+store_free_dns_answer(dnsa);
 return NULL;	/*XXX better error detail?  logging? */
 }
 
@@ -108,12 +114,15 @@ dkim_exim_verify_init(BOOL dot_stuffing)
 {
 dkim_exim_init();
 
-/* There is a store-reset between header & body reception
-so cannot use the main pool. Any allocs done by Exim
-memory-handling must use the perm pool. */
+/* There is a store-reset between header & body reception for the main pool
+(actually, after every header line) so cannot use that as we need the data we
+store per-header, during header processing, at the end of body reception
+for evaluating the signature.  Any allocs done for dkim verify
+memory-handling must use a different pool.  We use a separate one that we
+can reset per message. */
 
 dkim_verify_oldpool = store_pool;
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 
 /* Free previous context if there is one */
 
@@ -138,7 +147,7 @@ dkim_exim_verify_feed(uschar * data, int len)
 {
 int rc;
 
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 if (  dkim_collect_input
    && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK)
   {
@@ -304,7 +313,7 @@ int rc;
 gstring * g = NULL;
 const uschar * errstr = NULL;
 
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 
 /* Delete eventual previous signature chain */