Fixes CVE-2021-3746 libtpms: out-of-bounds access via specially crafted TPM 2 command packets

Resolves: rhbz#1999303

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

0001-tpm2-Initialize-a-whole-OBJECT-before-using-it.patch

@@ -0,0 +1,34 @@
+From 33a03986e0a09dde439985e0312d1c8fb3743aab Mon Sep 17 00:00:00 2001
+From: Stefan Berger <stefanb@linux.vnet.ibm.com>
+Date: Thu, 22 Jul 2021 21:23:58 -0400
+Subject: [PATCH 1/2] tpm2: Initialize a whole OBJECT before using it
+
+Initialize a whole OBJECT before using it. This is necessary since
+an OBJECT may also be used as a HASH_OBJECT via the ANY_OBJECT
+union and that HASH_OBJECT can leave bad size inidicators in TPM2B
+buffer in the OBJECT. To get rid of this problem we reset the whole
+OBJECT to 0 before using it. This is as if the memory for the
+OBJECT was just initialized.
+
+Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
+---
+ src/tpm2/Object.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/src/tpm2/Object.c b/src/tpm2/Object.c
+index 8e8b3ee..8406d8f 100644
+--- a/src/tpm2/Object.c
++++ b/src/tpm2/Object.c
+@@ -276,7 +276,8 @@ FindEmptyObjectSlot(
+ 		    if(handle)
+ 			*handle = i + TRANSIENT_FIRST;
+ 		    // Initialize the object attributes
+-		    MemorySet(&object->attributes, 0, sizeof(OBJECT_ATTRIBUTES));
++		    // MemorySet(&object->attributes, 0, sizeof(OBJECT_ATTRIBUTES));
++		    MemorySet(object, 0, sizeof(*object)); // libtpms added: Initialize the whole object
+ 		    return object;
+ 		}
+ 	}
+-- 
+2.33.0.rc2
+

0002-tpm2-NVMarshal-Handle-index-orderly-RAM-without-0-si.patch

@@ -0,0 +1,56 @@
+From aaef222e8682cc2e0f9ea7124220c5fe44fab62b Mon Sep 17 00:00:00 2001
+From: Stefan Berger <stefanb@linux.vnet.ibm.com>
+Date: Fri, 23 Jul 2021 13:29:00 -0400
+Subject: [PATCH 2/2] tpm2: NVMarshal: Handle index orderly RAM without 0-sized
+ terminating node
+
+The NVRAM entries in s_indexOrderlyRam array do not need to contain a
+0-sized terminating node. Instead, the entries may fill up this 512
+byte array so that no NV_RAM_HEADER structure fits anymore. The fact
+that no more NV_RAM_HEADER structure fits is also an indicator for the
+last entry. We need to account for this in the code marshalling and
+unmarshalling the entries so that we stop marshalling the entries
+then and similarly stop unmarshalling.
+
+Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
+---
+ src/tpm2/NVMarshal.c | 16 ++++++++++++++++
+ 1 file changed, 16 insertions(+)
+
+diff --git a/src/tpm2/NVMarshal.c b/src/tpm2/NVMarshal.c
+index f8a3798..935a76c 100644
+--- a/src/tpm2/NVMarshal.c
++++ b/src/tpm2/NVMarshal.c
+@@ -4244,6 +4244,12 @@ INDEX_ORDERLY_RAM_Marshal(void *array, size_t array_size,
+                                      datasize, buffer, size);
+         }
+         offset += nrh.size;
++        if (offset + sizeof(NV_RAM_HEADER) > array_size) {
++            /* nothing will fit anymore and there won't be a 0-sized
++             * terminating node (@1).
++             */
++            break;
++        }
+     }
+ 
+     written += BLOCK_SKIP_WRITE_PUSH(TRUE, buffer, size);
+@@ -4286,6 +4292,16 @@ INDEX_ORDERLY_RAM_Unmarshal(void *array, size_t array_size,
+          */
+         nrhp = array + offset;
+ 
++        if (offset + sizeof(NV_RAM_HEADER) > sourceside_size) {
++            /* this case can occur with the previous entry filling up the
++             * space; in this case there will not be a 0-sized terminating
++             * node (see @1 above). We clear the rest of our space.
++             */
++            if (array_size > offset)
++                memset(nrhp, 0, array_size - offset);
++            break;
++        }
++
+         /* write the NVRAM header;
+            nrh->size holds the complete size including data;
+            nrh->size = 0 indicates the end */
+-- 
+2.33.0.rc2
+

libtpms.spec

@@ -3,7 +3,7 @@
 
 Name:           libtpms
 Version:        0.8.2
-Release:        0.%{gitdate}git%{gitversion}%{?dist}.6
+Release:        0.%{gitdate}git%{gitversion}%{?dist}.7
 
 Summary: Library providing Trusted Platform Module (TPM) functionality
 License:        BSD
@@ -13,6 +13,8 @@ Patch0001:      0001-build-sys-leave-CFLAGS-LDFLAGS-for-user-to-be-define.patch
 Patch0002:      0001-tpm2-Reset-TPM2B-buffer-sizes-after-test-fails-for-v.patch
 Patch0003:      0002-tpm2-Add-maxSize-parameter-to-TPM2B_Marshal-for-sani.patch
 Patch0004:      0003-tpm2-Restore-original-value-if-unmarshalled-value-wa.patch
+Patch0005:      0001-tpm2-Initialize-a-whole-OBJECT-before-using-it.patch
+Patch0006:      0002-tpm2-NVMarshal-Handle-index-orderly-RAM-without-0-si.patch
 
 BuildRequires:  openssl-devel
 BuildRequires:  pkgconfig gawk sed
@@ -59,6 +61,10 @@ find %{buildroot} -type f -name '*.la' | xargs rm -f -- || :
 %{_mandir}/man3/*
 
 %changelog
+* Tue Aug 31 2021 Marc-André Lureau <marcandre.lureau@redhat.com> - 0.8.2-0.20210301git729fc6a4ca.7
+- Fixes CVE-2021-3746 libtpms: out-of-bounds access via specially crafted TPM 2 command packets
+  Resolves: rhbz#1999303
+
 * Mon Aug 09 2021 Mohan Boddu <mboddu@redhat.com> - 0.8.2-0.20210301git729fc6a4ca.6
 - Rebuilt for IMA sigs, glibc 2.34, aarch64 flags
   Related: rhbz#1991688