diff --git a/ChangeLog b/ChangeLog
index 9354fe1..1ee1cd4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -77,12 +77,19 @@
    * Add a check for invalid private parameters in ecdsa_sign.
      Reported by Yolan Romailler.
    * Fix word size check in in pk.c to not depend on MBEDTLS_HAVE_INT64.
+   * Add size-checks for record and handshake message content, securing
+     fragile yet non-exploitable code-paths.
+   * Fix crash when calling mbedtls_ssl_cache_free() twice. Found by
+     MilenkoMitrovic, #1104
 
 Changes
    * Extend cert_write example program by options to set the CRT version
      and the message digest. Further, allow enabling/disabling of authority
      identifier, subject identifier and basic constraints extensions.
 
+Features
+   * Allow comments in test data files.
+
 = mbed TLS 2.1.9 branch released 2017-08-10
 
 Security
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 9eb4a5f..060e43d 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -24,6 +24,7 @@
 #define MBEDTLS_SSL_INTERNAL_H
 
 #include "ssl.h"
+#include "cipher.h"
 
 #if defined(MBEDTLS_MD5_C)
 #include "md5.h"
@@ -134,14 +135,34 @@
 #define MBEDTLS_SSL_PADDING_ADD              0
 #endif
 
-#define MBEDTLS_SSL_BUFFER_LEN  ( MBEDTLS_SSL_MAX_CONTENT_LEN               \
-                        + MBEDTLS_SSL_COMPRESSION_ADD               \
-                        + 29 /* counter + header + IV */    \
-                        + MBEDTLS_SSL_MAC_ADD                       \
-                        + MBEDTLS_SSL_PADDING_ADD                   \
+#define MBEDTLS_SSL_PAYLOAD_LEN ( MBEDTLS_SSL_MAX_CONTENT_LEN    \
+                        + MBEDTLS_SSL_COMPRESSION_ADD            \
+                        + MBEDTLS_MAX_IV_LENGTH                  \
+                        + MBEDTLS_SSL_MAC_ADD                    \
+                        + MBEDTLS_SSL_PADDING_ADD                \
                         )
 
 /*
+ * Check that we obey the standard's message size bounds
+ */
+
+#if MBEDTLS_SSL_MAX_CONTENT_LEN > 16384
+#error Bad configuration - record content too large.
+#endif
+
+#if MBEDTLS_SSL_PAYLOAD_LEN > 16384 + 2048
+#error Bad configuration - protected record payload too large.
+#endif
+
+/* Note: Even though the TLS record header is only 5 bytes
+   long, we're internally using 8 bytes to store the
+   implicit sequence number. */
+#define MBEDTLS_SSL_HEADER_LEN 13
+
+#define MBEDTLS_SSL_BUFFER_LEN  \
+    ( ( MBEDTLS_SSL_HEADER_LEN ) + ( MBEDTLS_SSL_PAYLOAD_LEN ) )
+
+/*
  * TLS extension flags (for extensions with outgoing ServerHello content
  * that need it (e.g. for RENEGOTIATION_INFO the server already knows because
  * of state of the renegotiation flag, so no indicator is required)
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index 711bc53..14e350e 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -321,6 +321,7 @@
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_free( &cache->mutex );
 #endif
+    cache->chain = NULL;
 }
 
 #endif /* MBEDTLS_SSL_CACHE_C */
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index da08066..9d45532 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1262,6 +1262,14 @@
     MBEDTLS_SSL_DEBUG_BUF( 4, "before encrypt: output payload",
                       ssl->out_msg, ssl->out_msglen );
 
+    if( ssl->out_msglen > MBEDTLS_SSL_MAX_CONTENT_LEN )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Record content %u too large, maximum %d",
+                                    (unsigned) ssl->out_msglen,
+                                    MBEDTLS_SSL_MAX_CONTENT_LEN ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
     /*
      * Add MAC before if needed
      */
@@ -2731,6 +2739,15 @@
         if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
         {
             /* Make room for the additional DTLS fields */
+            if( MBEDTLS_SSL_MAX_CONTENT_LEN - ssl->out_msglen < 8 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS handshake message too large: "
+                              "size %u, maximum %u",
+                               (unsigned) ( ssl->in_hslen - 4 ),
+                               (unsigned) ( MBEDTLS_SSL_MAX_CONTENT_LEN - 12 ) ) );
+                return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+            }
+
             memmove( ssl->out_msg + 12, ssl->out_msg + 4, len - 4 );
             ssl->out_msglen += 8;
             len += 8;
diff --git a/tests/scripts/generate_code.pl b/tests/scripts/generate_code.pl
index 3491ece..7b45d9c 100755
--- a/tests/scripts/generate_code.pl
+++ b/tests/scripts/generate_code.pl
@@ -1,5 +1,26 @@
 #!/usr/bin/env perl
 #
+#       A test data file consists of a sequence of paragraphs separated by
+#       a single empty line. Line breaks may be in Unix (LF) or Windows (CRLF)
+#       format. Lines starting with the character '#' are ignored
+#       (the parser behaves as if they were not present).
+#
+#       Each paragraph describes one test case and must consist of: (1) one
+#       line which is the test case name; (2) an optional line starting with
+#       the 11-character prefix "depends_on:"; (3) a line containing the test
+#       function to execute and its parameters.
+#
+#       A depends_on: line consists of a list of compile-time options
+#       separated by the character ':', with no whitespace. The test case
+#       is executed only if this compilation option is enabled in config.h.
+#
+#       The last line of each paragraph contains a test function name and
+#       a list of parameters separated by the character ':'. Running the
+#       test case calls this function with the specified parameters. Each
+#       parameter may either be an integer written in decimal or hexadecimal,
+#       or a string surrounded by double quotes which may not contain the
+#       ':' character.
+#
 
 use strict;
 
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index bdbe55f..2c7c2cb 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -41,6 +41,7 @@
     printf "  -m|--memcheck\tCheck memory leaks and errors.\n"
     printf "  -f|--filter\tOnly matching tests are executed (default: '$FILTER')\n"
     printf "  -e|--exclude\tMatching tests are excluded (default: '$EXCLUDE')\n"
+    printf "     --seed\tInteger seed value to use for this test run (default: random)\n"
 }
 
 get_options() {
@@ -55,6 +56,9 @@
             -m|--memcheck)
                 MEMCHECK=1
                 ;;
+            --seed)
+                shift; SEED="$1"
+                ;;
             -h|--help)
                 print_usage
                 exit 0
@@ -564,7 +568,7 @@
 # +SRV_PORT will be replaced by either $SRV_PORT or $PXY_PORT later
 P_SRV="$P_SRV server_addr=127.0.0.1 server_port=$SRV_PORT"
 P_CLI="$P_CLI server_addr=127.0.0.1 server_port=+SRV_PORT"
-P_PXY="$P_PXY server_addr=127.0.0.1 server_port=$SRV_PORT listen_addr=127.0.0.1 listen_port=$PXY_PORT"
+P_PXY="$P_PXY server_addr=127.0.0.1 server_port=$SRV_PORT listen_addr=127.0.0.1 listen_port=$PXY_PORT ${SEED:+"seed=$SEED"}"
 O_SRV="$O_SRV -accept $SRV_PORT -dhparam data_files/dhparams.pem"
 O_CLI="$O_CLI -connect localhost:+SRV_PORT"
 G_SRV="$G_SRV -p $SRV_PORT"
diff --git a/tests/suites/main_test.function b/tests/suites/main_test.function
index 420ee76..db968e1 100644
--- a/tests/suites/main_test.function
+++ b/tests/suites/main_test.function
@@ -133,18 +133,31 @@
     return( ret );
 }
 
+/** Retrieve one input line into buf, which must have room for len
+ * bytes. The trailing line break (if any) is stripped from the result.
+ * Lines beginning with the character '#' are skipped. Lines that are
+ * more than len-1 bytes long including the trailing line break are
+ * truncated; note that the following bytes remain in the input stream.
+ *
+ * \return 0 on success, -1 on error or end of file
+ */
 int get_line( FILE *f, char *buf, size_t len )
 {
     char *ret;
 
-    ret = fgets( buf, len, f );
-    if( ret == NULL )
-        return( -1 );
+    do
+    {
+        ret = fgets( buf, len, f );
+        if( ret == NULL )
+            return( -1 );
+    }
+    while( buf[0] == '#' );
 
-    if( strlen( buf ) && buf[strlen(buf) - 1] == '\n' )
-        buf[strlen(buf) - 1] = '\0';
-    if( strlen( buf ) && buf[strlen(buf) - 1] == '\r' )
-        buf[strlen(buf) - 1] = '\0';
+    ret = buf + strlen( buf );
+    if( ret-- > buf && *ret == '\n' )
+        *ret = '\0';
+    if( ret-- > buf && *ret == '\r' )
+        *ret = '\0';
 
     return( 0 );
 }
diff --git a/tests/suites/test_suite_md.data b/tests/suites/test_suite_md.data
index 71d1f6d..abd8e55 100644
--- a/tests/suites/test_suite_md.data
+++ b/tests/suites/test_suite_md.data
@@ -1,3 +1,4 @@
+# Tests of the generic message digest interface
 MD process
 mbedtls_md_process:
 
diff --git a/tests/suites/test_suite_mdx.data b/tests/suites/test_suite_mdx.data
index 2d403b4..3d063a4 100644
--- a/tests/suites/test_suite_mdx.data
+++ b/tests/suites/test_suite_mdx.data
@@ -1,3 +1,4 @@
+# Test MD2, MD4, MD5 and RIPEMD160
 mbedtls_md2 Test vector RFC1319 #1
 md2_text:"":"8350e5a3e24c153df2275c9f80692773"
 
diff --git a/tests/suites/test_suite_rsa.data b/tests/suites/test_suite_rsa.data
index 5013ac8..fc7d935 100644
--- a/tests/suites/test_suite_rsa.data
+++ b/tests/suites/test_suite_rsa.data
@@ -1,5 +1,6 @@
 RSA PKCS1 Verify v1.5 CAVS #1
 depends_on:MBEDTLS_SHA1_C:MBEDTLS_PKCS1_V15
+# Good padding but wrong hash
 mbedtls_rsa_pkcs1_verify:"d6248c3e96b1a7e5fea978870fcc4c9786b4e5156e16b7faef4557d667f730b8bc4c784ef00c624df5309513c3a5de8ca94c2152e0459618666d3148092562ebc256ffca45b27fd2d63c68bd5e0a0aefbe496e9e63838a361b1db6fc272464f191490bf9c029643c49d2d9cd08833b8a70b4b3431f56fb1eb55ccd39e77a9c92":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA1:1024:16:"e28a13548525e5f36dccb24ecb7cc332cc689dfd64012604c9c7816d72a16c3f5fcdc0e86e7c03280b1c69b586ce0cd8aec722cc73a5d3b730310bf7dfebdc77ce5d94bbc369dc18a2f7b07bd505ab0f82224aef09fdc1e5063234255e0b3c40a52e9e8ae60898eb88a766bdd788fe9493d8fd86bcdd2884d5c06216c65469e5":16:"3":"3203b7647fb7e345aa457681e5131777f1adc371f2fba8534928c4e52ef6206a856425d6269352ecbf64db2f6ad82397768cafdd8cd272e512d617ad67992226da6bc291c31404c17fd4b7e2beb20eff284a44f4d7af47fd6629e2c95809fa7f2241a04f70ac70d3271bb13258af1ed5c5988c95df7fa26603515791075feccd":MBEDTLS_ERR_RSA_VERIFY_FAILED
 
 RSA PKCS1 Verify v1.5 CAVS #2
@@ -24,6 +25,7 @@
 
 RSA PKCS1 Verify v1.5 CAVS #7
 depends_on:MBEDTLS_SHA512_C:MBEDTLS_PKCS1_V15
+# Bad padding after performing the public key operation
 mbedtls_rsa_pkcs1_verify:"d03f12276f6ba7545b8fce719471bd253791878809694e8754f3b389f26c9253a758ed28b4c62535a8d5702d7a778731d5759ff2b3b39b192db680e791632918b6093c0e8ca25c2bf756a07fde4144a37f769fe4054455a45cb8cefe4462e7a9a45ce71f2189b4fef01b47aee8585d44dc9d6fa627a3e5f08801871731f234cd":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA384:1024:16:"e28a13548525e5f36dccb24ecb7cc332cc689dfd64012604c9c7816d72a16c3f5fcdc0e86e7c03280b1c69b586ce0cd8aec722cc73a5d3b730310bf7dfebdc77ce5d94bbc369dc18a2f7b07bd505ab0f82224aef09fdc1e5063234255e0b3c40a52e9e8ae60898eb88a766bdd788fe9493d8fd86bcdd2884d5c06216c65469e5":16:"3":"d93a878c1ce86571590b0e43794b3edb23552797c4b8c9e3da4fe1cc4ac0566acd3b10541fe9a7a79f5ea4892d3069ca6903efb5c40c47eb8a9c781eb4249281d40c3d96aae16da1bb4daaece6a26eca5f41c062b4124a64fc9d340cba5ab0d1f5affff6515a87f0933774fd4322d2fa497cd6f708a429ca56dcb1fd3db623d0":MBEDTLS_ERR_RSA_INVALID_PADDING
 
 RSA PKCS1 Verify v1.5 CAVS #8
@@ -365,6 +367,7 @@
 mbedtls_rsa_gen_key:2048:3:0
 
 RSA Generate Key - 1025 bit key
+# mbedtls_rsa_gen_key only supports even-sized keys
 mbedtls_rsa_gen_key:1025:3:MBEDTLS_ERR_RSA_BAD_INPUT_DATA
 
 RSA PKCS1 Encrypt Bad RNG
diff --git a/tests/suites/test_suite_shax.data b/tests/suites/test_suite_shax.data
index ea2a183..ee8074d 100644
--- a/tests/suites/test_suite_shax.data
+++ b/tests/suites/test_suite_shax.data
@@ -1,3 +1,4 @@
+# Test the operation of SHA-1 and SHA-2
 SHA-1 Test Vector NIST CAVS #1
 depends_on:MBEDTLS_SHA1_C
 mbedtls_sha1:"":"da39a3ee5e6b4b0d3255bfef95601890afd80709"