From fc96555ab63243de9d468325aeaaa14cd77b9943 Mon Sep 17 00:00:00 2001
From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Sat, 9 Jan 2021 13:08:35 +0000
Subject: [PATCH] Utilities: harden exim_tidydb against corrupt wait-records. 
 Bug 2343

---
 src/src/exim_dbutil.c | 30 ++++++++++++++++++++++++++----
 src/src/macros.h      |  3 ++-
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/src/exim_dbutil.c b/src/src/exim_dbutil.c
index 742952758..7ca7a3073 100644
--- a/src/src/exim_dbutil.c
+++ b/src/src/exim_dbutil.c
@@ -388,7 +388,7 @@ pick out the timestamps, etc., do the copying centrally here.
 Arguments:
   dbblock   a pointer to an open database block
   key       the key of the record to be read
-  length    where to put the length (or NULL if length not wanted)
+  length    where to put the length (or NULL if length not wanted). Includes overhead.
 
 Returns: a pointer to the retrieved record, or
          NULL if the record is not found
@@ -416,7 +416,7 @@ we should store the taint status along with the data. */
 
 yield = store_get(EXIM_DATUM_SIZE(result_datum), TRUE);
 memcpy(yield, EXIM_DATUM_DATA(result_datum), EXIM_DATUM_SIZE(result_datum));
-if (length != NULL) *length = EXIM_DATUM_SIZE(result_datum);
+if (length) *length = EXIM_DATUM_SIZE(result_datum);
 
 EXIM_DATUM_FREE(result_datum);    /* Some DBM libs require freeing */
 return yield;
@@ -616,6 +616,7 @@ for (uschar * key = dbfn_scan(dbm, TRUE, &cursor);
 	t = wait->text;
 	name[MESSAGE_ID_LENGTH] = 0;
 
+    /* Leave corrupt records alone */
 	if (wait->count > WAIT_NAME_MAX)
 	  {
 	  fprintf(stderr,
@@ -1218,7 +1219,7 @@ for (; keychain && (reset_point = store_mark()); store_reset(reset_point))
   /* A continuation record may have been deleted or renamed already, so
   non-existence is not serious. */
 
-  if (value == NULL) continue;
+  if (!value) continue;
 
   /* Delete if too old */
 
@@ -1239,12 +1240,33 @@ for (; keychain && (reset_point = store_mark()); store_reset(reset_point))
 
     /* Leave corrupt records alone */
 
+    if (wait->time_stamp > time(NULL))
+      {
+      printf("**** Data for '%s' corrupted\n  time in future: %s\n",
+        key, print_time(((dbdata_generic *)value)->time_stamp));
+      continue;
+      }
     if (wait->count > WAIT_NAME_MAX)
       {
-      printf("**** Data for %s corrupted\n  count=%d=0x%x max=%d\n",
+      printf("**** Data for '%s' corrupted\n  count=%d=0x%x max=%d\n",
         key, wait->count, wait->count, WAIT_NAME_MAX);
       continue;
       }
+    if (wait->sequence > WAIT_CONT_MAX)
+      {
+      printf("**** Data for '%s' corrupted\n  sequence=%d=0x%x max=%d\n",
+        key, wait->sequence, wait->sequence, WAIT_CONT_MAX);
+      continue;
+      }
+
+    /* Record over 1 year old; just remove it */
+
+    if (wait->time_stamp < time(NULL) - 365*24*60*60)
+      {
+      dbfn_delete(dbm, key);
+      printf("deleted %s (too old)\n", key);
+      continue;
+      }
 
     /* Loop for renamed continuation records. For each message id,
     check to see if the message exists, and if not, remove its entry
diff --git a/src/src/macros.h b/src/src/macros.h
index a584551d3..68470a9f1 100644
--- a/src/src/macros.h
+++ b/src/src/macros.h
@@ -192,9 +192,10 @@ message id with a trailing "-H" or "-D" added. */
 #define SPOOL_NAME_LENGTH (MESSAGE_ID_LENGTH+2)
 
 /* The maximum number of message ids to store in a waiting database
-record. */
+record, and the max number of continuation records allowed. */
 
 #define WAIT_NAME_MAX 50
+#define WAIT_CONT_MAX 1000
 
 /* Fixed option values for all PCRE functions */
 
-- 
2.30.2