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From 05b66529117d1cd85a636ab7d8fc84abdec814de Mon Sep 17 00:00:00 2001
From: William Brown <william@blackhats.net.au>
Date: Thu, 12 Nov 2020 13:04:21 +1000
Subject: [PATCH] Issue 4428 - BUG Paged Results with critical false causes
 sigsegv in chaining

Bug Description: When a paged search through chaining backend is
received with a false criticality (such as SSSD), chaining backend
will sigsegv due to a null context.

Fix Description: When a NULL ctx is recieved to be freed, this is
as paged results have finished being sent, so we check the NULL
ctx and move on.

fixes: #4428

Author: William Brown <william@blackhats.net.au>

Review by: @droideck, @mreynolds389
---
 ldap/servers/plugins/chainingdb/cb_search.c | 6 ++++++
 ldap/servers/plugins/chainingdb/cb_utils.c  | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/ldap/servers/plugins/chainingdb/cb_search.c b/ldap/servers/plugins/chainingdb/cb_search.c
index 69d23a6b5..d47cbc8e4 100644
--- a/ldap/servers/plugins/chainingdb/cb_search.c
+++ b/ldap/servers/plugins/chainingdb/cb_search.c
@@ -740,6 +740,12 @@ chaining_back_search_results_release(void **sr)
 
     slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                   "chaining_back_search_results_release\n");
+    if (ctx == NULL) {
+        /* The paged search is already complete, just return */
+        /* Could we have a ctx state flag instead? */
+        return;
+    }
+
     if (ctx->readahead != ctx->tobefreed) {
         slapi_entry_free(ctx->readahead);
     }
diff --git a/ldap/servers/plugins/chainingdb/cb_utils.c b/ldap/servers/plugins/chainingdb/cb_utils.c
index dfd5dd92c..d52fd25a6 100644
--- a/ldap/servers/plugins/chainingdb/cb_utils.c
+++ b/ldap/servers/plugins/chainingdb/cb_utils.c
@@ -279,7 +279,11 @@ cb_add_suffix(cb_backend_instance *inst, struct berval **bvals, int apply_mod, c
     return LDAP_SUCCESS;
 }
 
+#ifdef DEBUG
+static int debug_on = 1;
+#else
 static int debug_on = 0;
+#endif
 
 int
 cb_debug_on()
-- 
2.26.2