1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
From ff5bacf17c2451e9d48c78a5ef96ec0c376ff33d Mon Sep 17 00:00:00 2001
From: Matthijs Mekking <matthijs@isc.org>
Date: Thu, 1 Jun 2023 10:03:48 +0200
Subject: [PATCH] Fix serve-stale hang at shutdown
The 'refresh_rrset' variable is used to determine if we can detach from
the client. This can cause a hang on shutdown. To fix this, move setting
of the 'nodetach' variable up to where 'refresh_rrset' is set (in
query_lookup(), and thus not in ns_query_done()), and set it to false
when actually refreshing the RRset, so that when this lookup is
completed, the client will be detached.
Patch taken from :https://downloads.isc.org/isc/bind9/9.18.16/patches/0003-CVE-2023-2911.patch
Upstream-Status: Backport [https://gitlab.isc.org/isc-projects/bind9/-/commit/240caa32b9cab90a38ab863fd64e6becf5d1393c && https://gitlab.isc.org/isc-projects/bind9/-/commit/ff5bacf17c2451e9d48c78a5ef96ec0c376ff33d]
CVE: CVE-2023-2911
Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
---
lib/ns/query.c | 30 ++++++++++++++++++++++--------
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/lib/ns/query.c b/lib/ns/query.c
index 0d2ba6b..8945dd4 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -5824,6 +5824,7 @@ query_refresh_rrset(query_ctx_t *orig_qctx) {
qctx.client->query.dboptions &= ~(DNS_DBFIND_STALETIMEOUT |
DNS_DBFIND_STALEOK |
DNS_DBFIND_STALEENABLED);
+ qctx.client->nodetach = false;
/*
* We'll need some resources...
@@ -6076,7 +6077,14 @@ query_lookup(query_ctx_t *qctx) {
"%s stale answer used, an attempt to "
"refresh the RRset will still be made",
namebuf);
+
qctx->refresh_rrset = STALE(qctx->rdataset);
+ /*
+ * If we are refreshing the RRSet, we must not
+ * detach from the client in query_send().
+ */
+ qctx->client->nodetach = qctx->refresh_rrset;
+
ns_client_extendederror(
qctx->client, ede,
"stale data prioritized over lookup");
@@ -6503,7 +6511,7 @@ ns_query_recurse(ns_client_t *client, dns_rdatatype_t qtype, dns_name_t *qname,
if (recparam_match(&client->query.recparam, qtype, qname, qdomain)) {
ns_client_log(client, NS_LOGCATEGORY_CLIENT, NS_LOGMODULE_QUERY,
ISC_LOG_INFO, "recursion loop detected");
- return (ISC_R_FAILURE);
+ return (ISC_R_ALREADYRUNNING);
}
recparam_update(&client->query.recparam, qtype, qname, qdomain);
@@ -7620,10 +7628,21 @@ query_usestale(query_ctx_t *qctx, isc_result_t result) {
return (false);
}
- if (result == DNS_R_DUPLICATE || result == DNS_R_DROP) {
+ if (qctx->refresh_rrset) {
+ /*
+ * This is a refreshing query, we have already prioritized
+ * stale data, so don't enable serve-stale again.
+ */
+ return (false);
+ }
+
+ if (result == DNS_R_DUPLICATE || result == DNS_R_DROP ||
+ result == ISC_R_ALREADYRUNNING)
+ {
/*
* Don't enable serve-stale if the result signals a duplicate
- * query or query that is being dropped.
+ * query or a query that is being dropped or can't proceed
+ * because of a recursion loop.
*/
return (false);
}
@@ -11927,12 +11946,7 @@ ns_query_done(query_ctx_t *qctx) {
/*
* Client may have been detached after query_send(), so
* we test and store the flag state here, for safety.
- * If we are refreshing the RRSet, we must not detach from the client
- * in the query_send(), so we need to override the flag.
*/
- if (qctx->refresh_rrset) {
- qctx->client->nodetach = true;
- }
nodetach = qctx->client->nodetach;
query_send(qctx->client);
--
2.25.1
|
