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From 1171111657081970585f9f0e03b476358c33a6c0 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Wed, 12 Oct 2016 20:36:52 +0900
Subject: [PATCH]
4467. [security] It was possible to trigger an assertion when
rendering a message. (CVE-2016-2776) [RT #43139]
Backport commit 2bd0922cf995b9ac205fc83baf7e220b95c6bf12 from the
v9.11.0_patch branch.
CVE: CVE-2016-2776
Upstream-Status: Backport
Signed-off-by: zhengruoqin <zhengrq.fnst@cn.fujitsu.com>
---
CHANGES | 3 +++
lib/dns/message.c | 42 +++++++++++++++++++++++++++++++-----------
2 files changed, 34 insertions(+), 11 deletions(-)
diff --git a/CHANGES b/CHANGES
index d0a9d12..5c8c61a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4467. [security] It was possible to trigger an assertion when
+ rendering a message. (CVE-2016-2776) [RT #43139]
+
4406. [security] getrrsetbyname with a non absolute name could
trigger an infinite recursion bug in lwresd
and named with lwres configured if when combined
diff --git a/lib/dns/message.c b/lib/dns/message.c
index 6b5b4bb..b74dc81 100644
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@@ -1754,7 +1754,7 @@ dns_message_renderbegin(dns_message_t *msg, dns_compress_t *cctx,
if (r.length < DNS_MESSAGE_HEADERLEN)
return (ISC_R_NOSPACE);
- if (r.length < msg->reserved)
+ if (r.length - DNS_MESSAGE_HEADERLEN < msg->reserved)
return (ISC_R_NOSPACE);
/*
@@ -1895,8 +1895,29 @@ norender_rdataset(const dns_rdataset_t *rdataset, unsigned int options,
return (ISC_TRUE);
}
-
#endif
+
+static isc_result_t
+renderset(dns_rdataset_t *rdataset, dns_name_t *owner_name,
+ dns_compress_t *cctx, isc_buffer_t *target,
+ unsigned int reserved, unsigned int options, unsigned int *countp)
+{
+ isc_result_t result;
+
+ /*
+ * Shrink the space in the buffer by the reserved amount.
+ */
+ if (target->length - target->used < reserved)
+ return (ISC_R_NOSPACE);
+
+ target->length -= reserved;
+ result = dns_rdataset_towire(rdataset, owner_name,
+ cctx, target, options, countp);
+ target->length += reserved;
+
+ return (result);
+}
+
isc_result_t
dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
unsigned int options)
@@ -1939,6 +1960,8 @@ dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
/*
* Shrink the space in the buffer by the reserved amount.
*/
+ if (msg->buffer->length - msg->buffer->used < msg->reserved)
+ return (ISC_R_NOSPACE);
msg->buffer->length -= msg->reserved;
total = 0;
@@ -2214,9 +2237,8 @@ dns_message_renderend(dns_message_t *msg) {
* Render.
*/
count = 0;
- result = dns_rdataset_towire(msg->opt, dns_rootname,
- msg->cctx, msg->buffer, 0,
- &count);
+ result = renderset(msg->opt, dns_rootname, msg->cctx,
+ msg->buffer, msg->reserved, 0, &count);
msg->counts[DNS_SECTION_ADDITIONAL] += count;
if (result != ISC_R_SUCCESS)
return (result);
@@ -2232,9 +2254,8 @@ dns_message_renderend(dns_message_t *msg) {
if (result != ISC_R_SUCCESS)
return (result);
count = 0;
- result = dns_rdataset_towire(msg->tsig, msg->tsigname,
- msg->cctx, msg->buffer, 0,
- &count);
+ result = renderset(msg->tsig, msg->tsigname, msg->cctx,
+ msg->buffer, msg->reserved, 0, &count);
msg->counts[DNS_SECTION_ADDITIONAL] += count;
if (result != ISC_R_SUCCESS)
return (result);
@@ -2255,9 +2276,8 @@ dns_message_renderend(dns_message_t *msg) {
* the owner name of a SIG(0) is irrelevant, and will not
* be set in a message being rendered.
*/
- result = dns_rdataset_towire(msg->sig0, dns_rootname,
- msg->cctx, msg->buffer, 0,
- &count);
+ result = renderset(msg->sig0, dns_rootname, msg->cctx,
+ msg->buffer, msg->reserved, 0, &count);
msg->counts[DNS_SECTION_ADDITIONAL] += count;
if (result != ISC_R_SUCCESS)
return (result);
--
2.7.4
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