File ovmf-bsc1127821-dns-check-packet-size.patch of Package ovmf.10928
From e91ad444c474b4ae432fa1a7a494617463271d03 Mon Sep 17 00:00:00 2001
From: Jiaxin Wu <Jiaxin.wu@intel.com>
Date: Mon, 2 Jul 2018 09:20:56 +0800
Subject: [PATCH 1/1] NetworkPkg/DnsDxe: [CVE-2018-12178] Check the received
packet size before parsing the message.
Fix CVE-2018-12178
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=809
The DNS driver only checks the received packet size against the
minimum DNS header size in DnsOnPacketReceived(), later it accesses
the QueryName and QuerySection beyond the header scope, which might
cause the pointer within DNS driver points to an invalid entry or
modifies the memory content beyond the header scope.
This patch is to fix above problem.
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Wang Fan <fan.wang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Siyuan Fu <siyuan.fu@intel.com>
(cherry picked from commit 84110bbe4bb3a346514b9bb12eadb7586bca7dfd)
---
NetworkPkg/DnsDxe/DnsImpl.c | 85 +++++++++++++++++++++++++++++++------
NetworkPkg/DnsDxe/DnsImpl.h | 6 ++-
2 files changed, 75 insertions(+), 16 deletions(-)
diff --git a/NetworkPkg/DnsDxe/DnsImpl.c b/NetworkPkg/DnsDxe/DnsImpl.c
index ea3d27da5285..b943ece75708 100644
--- a/NetworkPkg/DnsDxe/DnsImpl.c
+++ b/NetworkPkg/DnsDxe/DnsImpl.c
@@ -1100,8 +1100,9 @@ IsValidDnsResponse (
@param Instance The DNS instance
@param RxString Received buffer.
- @param Completed Flag to indicate that Dns response is valid.
-
+ @param Length Received buffer length.
+ @param Completed Flag to indicate that Dns response is valid.
+
@retval EFI_SUCCESS Parse Dns Response successfully.
@retval Others Failed to parse Dns Response.
@@ -1110,12 +1111,14 @@ EFI_STATUS
ParseDnsResponse (
IN OUT DNS_INSTANCE *Instance,
IN UINT8 *RxString,
+ IN UINT32 Length,
OUT BOOLEAN *Completed
)
{
DNS_HEADER *DnsHeader;
CHAR8 *QueryName;
+ UINT32 QueryNameLen;
DNS_QUERY_SECTION *QuerySection;
CHAR8 *AnswerName;
@@ -1141,6 +1144,7 @@ ParseDnsResponse (
DNS6_RESOURCE_RECORD *Dns6RR;
EFI_STATUS Status;
+ UINT32 RemainingLength;
EFI_TPL OldTpl;
@@ -1164,7 +1168,18 @@ ParseDnsResponse (
*Completed = TRUE;
Status = EFI_SUCCESS;
-
+ RemainingLength = Length;
+
+ //
+ // Check whether the remaining packet length is avaiable or not.
+ //
+ if (RemainingLength <= sizeof (DNS_HEADER)) {
+ *Completed = FALSE;
+ return EFI_ABORTED;
+ } else {
+ RemainingLength -= sizeof (DNS_HEADER);
+ }
+
//
// Get header
//
@@ -1177,23 +1192,39 @@ ParseDnsResponse (
DnsHeader->AuthorityNum = NTOHS (DnsHeader->AuthorityNum);
DnsHeader->AditionalNum = NTOHS (DnsHeader->AditionalNum);
+ //
+ // There is always one QuestionsNum in DNS message. The capability to handle more
+ // than one requires to redesign the message format. Currently, it's not supported.
+ //
+ if (DnsHeader->QuestionsNum > 1) {
+ *Completed = FALSE;
+ return EFI_UNSUPPORTED;
+ }
+
//
// Get Query name
//
QueryName = (CHAR8 *) (RxString + sizeof (*DnsHeader));
+ QueryNameLen = (UINT32) AsciiStrLen (QueryName) + 1;
+
+ //
+ // Check whether the remaining packet length is avaiable or not.
+ //
+ if (RemainingLength <= QueryNameLen + sizeof (DNS_QUERY_SECTION)) {
+ *Completed = FALSE;
+ return EFI_ABORTED;
+ } else {
+ RemainingLength -= (QueryNameLen + sizeof (DNS_QUERY_SECTION));
+ }
+
//
// Get query section
//
- QuerySection = (DNS_QUERY_SECTION *) (QueryName + AsciiStrLen (QueryName) + 1);
+ QuerySection = (DNS_QUERY_SECTION *) (QueryName + QueryNameLen);
QuerySection->Type = NTOHS (QuerySection->Type);
QuerySection->Class = NTOHS (QuerySection->Class);
- //
- // Get Answer name
- //
- AnswerName = (CHAR8 *) QuerySection + sizeof (*QuerySection);
-
OldTpl = gBS->RaiseTPL (TPL_CALLBACK);
//
@@ -1327,10 +1358,26 @@ ParseDnsResponse (
Status = EFI_NOT_FOUND;
+ //
+ // Get Answer name
+ //
+ AnswerName = (CHAR8 *) QuerySection + sizeof (*QuerySection);
+
//
// Processing AnswerSection.
//
while (AnswerSectionNum < DnsHeader->AnswersNum) {
+ //
+ // Check whether the remaining packet length is avaiable or not.
+ //
+ if (RemainingLength <= sizeof (UINT16) + sizeof (DNS_ANSWER_SECTION)) {
+ *Completed = FALSE;
+ Status = EFI_ABORTED;
+ goto ON_EXIT;
+ } else {
+ RemainingLength -= (sizeof (UINT16) + sizeof (DNS_ANSWER_SECTION));
+ }
+
//
// Answer name should be PTR, else EFI_UNSUPPORTED returned.
//
@@ -1348,6 +1395,17 @@ ParseDnsResponse (
AnswerSection->Ttl = NTOHL (AnswerSection->Ttl);
AnswerSection->DataLength = NTOHS (AnswerSection->DataLength);
+ //
+ // Check whether the remaining packet length is avaiable or not.
+ //
+ if (RemainingLength < AnswerSection->DataLength) {
+ *Completed = FALSE;
+ Status = EFI_ABORTED;
+ goto ON_EXIT;
+ } else {
+ RemainingLength -= AnswerSection->DataLength;
+ }
+
//
// Check whether it's the GeneralLookUp querying.
//
@@ -1628,6 +1686,7 @@ DnsOnPacketReceived (
DNS_INSTANCE *Instance;
UINT8 *RcvString;
+ UINT32 Len;
BOOLEAN Completed;
@@ -1643,17 +1702,15 @@ DnsOnPacketReceived (
ASSERT (Packet != NULL);
- if (Packet->TotalSize <= sizeof (DNS_HEADER)) {
- goto ON_EXIT;
- }
-
+ Len = Packet->TotalSize;
+
RcvString = NetbufGetByte (Packet, 0, NULL);
ASSERT (RcvString != NULL);
//
// Parse Dns Response
//
- ParseDnsResponse (Instance, RcvString, &Completed);
+ ParseDnsResponse (Instance, RcvString, Len, &Completed);
ON_EXIT:
diff --git a/NetworkPkg/DnsDxe/DnsImpl.h b/NetworkPkg/DnsDxe/DnsImpl.h
index 5fa7f244c257..b64821f485a3 100644
--- a/NetworkPkg/DnsDxe/DnsImpl.h
+++ b/NetworkPkg/DnsDxe/DnsImpl.h
@@ -582,8 +582,9 @@ IsValidDnsResponse (
@param Instance The DNS instance
@param RxString Received buffer.
- @param Completed Flag to indicate that Dns response is valid.
-
+ @param Length Received buffer length.
+ @param Completed Flag to indicate that Dns response is valid.
+
@retval EFI_SUCCESS Parse Dns Response successfully.
@retval Others Failed to parse Dns Response.
@@ -592,6 +593,7 @@ EFI_STATUS
ParseDnsResponse (
IN OUT DNS_INSTANCE *Instance,
IN UINT8 *RxString,
+ IN UINT32 Length,
OUT BOOLEAN *Completed
);
--
2.20.1
