diff --git a/ChangeLog b/ChangeLog
index f440011..52c1bcb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,16 @@
 = mbed TLS 1.3.15 released 2015-10-xx
 
 Security
+   * Fix potential double free if ssl_set_psk() is called more than once and
+     some allocation fails. Cannot be forced remotely. Found by Guido Vranken,
+     Intelworks.
+   * Fix potential heap corruption on Windows when
+     x509_crt_parse_path() is passed a path longer than 2GB. Cannot be
+     triggered remotely. Found by Guido Vranken, Interlworks.
+   * Fix potential buffer overflow in some asn1_write_xxx() functions.
+     Cannot be triggered remotely unless you create X.509 certificates based
+     on untrusted input or write keys of untrusted origin. Found by Guido
+     Vranken, Interlworks.
    * The X509 max_pathlen constraint was not enforced on intermediate
      certificates. Found by Nicholas Wilson, fix and tests provided by
      Janos Follath. #280 and #319
diff --git a/library/asn1write.c b/library/asn1write.c
index 92282b1..6a7c9d3 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -88,7 +88,7 @@
 {
     size_t len = 0;
 
-    if( *p - start < (int) size )
+    if( *p < start || (size_t)( *p - start ) < size )
         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
 
     len = size;
@@ -108,7 +108,7 @@
     //
     len = mpi_size( X );
 
-    if( *p - start < (int) len )
+    if( *p < start || (size_t)( *p - start ) < len )
         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
 
     (*p) -= len;
@@ -271,7 +271,7 @@
 
     // Calculate byte length
     //
-    if( *p - start < (int) size + 1 )
+    if( *p < start || (size_t)( *p - start ) < size + 1 )
         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
 
     len = size + 1;
diff --git a/library/pkwrite.c b/library/pkwrite.c
index 35dbd0b..bb9514e 100644
--- a/library/pkwrite.c
+++ b/library/pkwrite.c
@@ -97,7 +97,7 @@
         return( ret );
     }
 
-    if( *p - start < (int) len )
+    if( *p < start || (size_t)( *p - start ) < len )
         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
 
     *p -= len;
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 44e5582..d9eb0a9 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -949,11 +949,16 @@
 #if defined(POLARSSL_KEY_EXCHANGE_PSK_ENABLED)
     if( key_ex == POLARSSL_KEY_EXCHANGE_PSK )
     {
-        if( end - p < 2 + (int) ssl->psk_len )
+        if( end - p < 2 )
             return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
 
         *(p++) = (unsigned char)( ssl->psk_len >> 8 );
         *(p++) = (unsigned char)( ssl->psk_len      );
+
+        if( end < p || (size_t)( end - p ) < ssl->psk_len )
+            return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+
+        memset( p, 0, ssl->psk_len );
         p += ssl->psk_len;
     }
     else
@@ -1021,11 +1026,15 @@
     }
 
     /* opaque psk<0..2^16-1>; */
-    if( end - p < 2 + (int) ssl->psk_len )
-            return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+    if( end - p < 2 )
+        return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
 
     *(p++) = (unsigned char)( ssl->psk_len >> 8 );
     *(p++) = (unsigned char)( ssl->psk_len      );
+
+    if( end < p || (size_t)( end - p ) < ssl->psk_len )
+        return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+
     memcpy( p, ssl->psk, ssl->psk_len );
     p += ssl->psk_len;
 
@@ -4082,6 +4091,8 @@
     {
         polarssl_free( ssl->psk );
         polarssl_free( ssl->psk_identity );
+        ssl->psk = NULL;
+        ssl->psk_identity = NULL;
     }
 
     if( ( ssl->psk = polarssl_malloc( psk_len ) ) == NULL ||
diff --git a/library/x509_create.c b/library/x509_create.c
index f505bab..b2cbdd4 100644
--- a/library/x509_create.c
+++ b/library/x509_create.c
@@ -265,13 +265,16 @@
     int ret;
     size_t len = 0;
 
-    if( *p - start < (int) size + 1 )
+    if( *p < start || (size_t)( *p - start ) < size )
         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
 
     len = size;
     (*p) -= len;
     memcpy( *p, sig, len );
 
+    if( *p - start < 1 )
+        return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
+
     *--(*p) = 0;
     len += 1;
 
diff --git a/library/x509_crt.c b/library/x509_crt.c
index cb63b13..92a9b17 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -973,7 +973,7 @@
     WCHAR szDir[MAX_PATH];
     char filename[MAX_PATH];
     char *p;
-    int len = (int) strlen( path );
+    size_t len = strlen( path );
 
     WIN32_FIND_DATAW file_data;
     HANDLE hFind;
@@ -1007,7 +1007,7 @@
 
         w_ret = WideCharToMultiByte( CP_ACP, 0, file_data.cFileName,
                                      lstrlenW( file_data.cFileName ),
-                                     p, len - 1,
+                                     p, (int) len - 1,
                                      NULL, NULL );
         if( w_ret == 0 )
             return( POLARSSL_ERR_X509_FILE_IO_ERROR );