Merge pull request #6391 from davidhorstmann-arm/fix-x509-get-name-cleanup

The Open CI ran successfully thus I think we can ignore the internal CI. 
diff --git a/ChangeLog.d/fix_x509_get_name_mem_leak.txt b/ChangeLog.d/fix_x509_get_name_mem_leak.txt
new file mode 100644
index 0000000..358d1af
--- /dev/null
+++ b/ChangeLog.d/fix_x509_get_name_mem_leak.txt
@@ -0,0 +1,4 @@
+Bugfix
+    * Fix memory leak in ssl_parse_certificate_request() caused by
+      mbedtls_x509_get_name() not freeing allocated objects in case of error.
+      Change mbedtls_x509_get_name() to clean up allocated objects on error.
diff --git a/library/x509.c b/library/x509.c
index ca2e907..c5b0161 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -459,6 +459,11 @@
  * For the general case we still use a flat list, but we mark elements of the
  * same set so that they are "merged" together in the functions that consume
  * this list, eg mbedtls_x509_dn_gets().
+ *
+ * On success, this function may allocate a linked list starting at cur->next
+ * that must later be free'd by the caller using mbedtls_free(). In error
+ * cases, this function frees all allocated memory internally and the caller
+ * has no freeing responsibilities.
  */
 int mbedtls_x509_get_name( unsigned char **p, const unsigned char *end,
                    mbedtls_x509_name *cur )
@@ -466,6 +471,8 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t set_len;
     const unsigned char *end_set;
+    mbedtls_x509_name *head = cur;
+    mbedtls_x509_name *prev, *allocated;
 
     /* don't use recursion, we'd risk stack overflow if not optimized */
     while( 1 )
@@ -475,14 +482,17 @@
          */
         if( ( ret = mbedtls_asn1_get_tag( p, end, &set_len,
                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET ) ) != 0 )
-            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME, ret ) );
+        {
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME, ret );
+            goto error;
+        }
 
         end_set  = *p + set_len;
 
         while( 1 )
         {
             if( ( ret = x509_get_attr_type_value( p, end_set, cur ) ) != 0 )
-                return( ret );
+                goto error;
 
             if( *p == end_set )
                 break;
@@ -493,7 +503,10 @@
             cur->next = mbedtls_calloc( 1, sizeof( mbedtls_x509_name ) );
 
             if( cur->next == NULL )
-                return( MBEDTLS_ERR_X509_ALLOC_FAILED );
+            {
+                ret = MBEDTLS_ERR_X509_ALLOC_FAILED;
+                goto error;
+            }
 
             cur = cur->next;
         }
@@ -507,10 +520,30 @@
         cur->next = mbedtls_calloc( 1, sizeof( mbedtls_x509_name ) );
 
         if( cur->next == NULL )
-            return( MBEDTLS_ERR_X509_ALLOC_FAILED );
+        {
+            ret = MBEDTLS_ERR_X509_ALLOC_FAILED;
+            goto error;
+        }
 
         cur = cur->next;
     }
+
+error:
+    /* Skip the first element as we did not allocate it */
+    allocated = head->next;
+
+    while( allocated != NULL )
+    {
+        prev = allocated;
+        allocated = allocated->next;
+
+        mbedtls_platform_zeroize( prev, sizeof( *prev ) );
+        mbedtls_free( prev );
+    }
+
+    mbedtls_platform_zeroize( head, sizeof( *head ) );
+
+    return( ret );
 }
 
 static int x509_parse_int( unsigned char **p, size_t n, int *res )
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 6263fba..8dd3379 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -415,6 +415,46 @@
 X509 Get Next DN #4 Consecutive Multivalue RDNs
 mbedtls_x509_dn_get_next:"C=NL, O=PolarSSL, title=Example, CN=PolarSSL Server 1":0x05:"C title":2:"C=NL + O=PolarSSL, title=Example + CN=PolarSSL Server 1"
 
+# Parse the following valid DN:
+#
+# 31 0B <- Set of
+#     30 09 <- Sequence of
+#         06 03 55 04 06 <- OID 2.5.4.6 countryName (C)
+#         13 02 4E 4C <- PrintableString "NL"
+# 31 11 <- Set of
+#     30 0F <- Sequence of
+#         06 03 55 04 0A <- OID 2.5.4.10 organizationName (O)
+#         0C 08 50 6F 6C 61 72 53 53 4C <- UTF8String "PolarSSL"
+# 31 19 <- Set of
+#     30 17 <- Sequence of
+#         06 03 55 04 03 <- OID 2.5.4.3 commonName (CN)
+#         0C 10 50 6F 6C 61 72 53 53 4C 20 54 65 73 74 20 43 41 <- UTF8String "PolarSSL Test CA"
+#
+X509 Get Name Valid DN
+mbedtls_x509_get_name:"310B3009060355040613024E4C3111300F060355040A0C08506F6C617253534C3119301706035504030C10506F6C617253534C2054657374204341":0
+
+# Parse the following corrupted DN:
+#
+# 31 0B <- Set of
+#     30 09 <- Sequence of
+#         06 03 55 04 06 <- OID 2.5.4.6 countryName (C)
+#         13 02 4E 4C <- PrintableString "NL"
+# 31 11 <- Set of
+#     30 0F <- Sequence of
+#         06 03 55 04 0A <- OID 2.5.4.10 organizationName (O)
+#         0C 08 50 6F 6C 61 72 53 53 4C <- UTF8String "PolarSSL"
+# 30 19 <- Sequence of (corrupted)
+#     30 17 <- Sequence of
+#         06 03 55 04 03 <- OID 2.5.4.3 commonName (CN)
+#         0C 10 50 6F 6C 61 72 53 53 4C 20 54 65 73 74 20 43 41 <- UTF8String "PolarSSL Test CA"
+#
+# The third 'Set of' is corrupted to instead be a 'Sequence of', causing an
+# error and forcing mbedtls_x509_get_name() to clean up the names it has
+# already allocated.
+#
+X509 Get Name Corrupted DN Mem Leak
+mbedtls_x509_get_name:"310B3009060355040613024E4C3111300F060355040A0C08506F6C617253534C3019301706035504030C10506F6C617253534C2054657374204341":MBEDTLS_ERR_X509_INVALID_NAME + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG
+
 X509 Time Expired #1
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_HAVE_TIME_DATE:MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA_BASED_ON_USE_PSA
 mbedtls_x509_time_is_past:"data_files/server1.crt":"valid_from":1
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index 60e703a..a3606f2 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -818,6 +818,41 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C */
+void mbedtls_x509_get_name( char * rdn_sequence, int exp_ret )
+{
+    unsigned char *name;
+    unsigned char *p;
+    size_t name_len;
+    mbedtls_x509_name head;
+    mbedtls_x509_name *allocated, *prev;
+    int ret;
+
+    memset( &head, 0, sizeof( head ) );
+
+    name = mbedtls_test_unhexify_alloc( rdn_sequence, &name_len );
+    p = name;
+
+    ret = mbedtls_x509_get_name( &p, ( name + name_len ), &head );
+    if( ret == 0 )
+    {
+        allocated = head.next;
+
+        while( allocated != NULL )
+        {
+            prev = allocated;
+            allocated = allocated->next;
+
+            mbedtls_free( prev );
+        }
+    }
+
+    TEST_EQUAL( ret, exp_ret );
+
+    mbedtls_free( name );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_X509_CREATE_C:MBEDTLS_X509_USE_C:MBEDTLS_X509_CRT_PARSE_C:!MBEDTLS_X509_REMOVE_INFO */
 void mbedtls_x509_dn_get_next( char * name_str, int next_merged, char * expected_oids, int exp_count, char * exp_dn_gets )
 {