commit c60f3528a1d4d147f45cb73b3698f1395b67a647
Author: Duncan Palmer <duncan.palmer@csiro.au>
Date:   Fri Feb 9 10:01:36 2018 +1000

    tpm2_nv(read|write): use a default buffer size if TPM reports 0.
    
    On a NUC5i7RYH, the TPM reports it's max NV buffer size as 0, which
    means we can neither read nor write. In this case, default to
    MAX_NV_BUFFER_SIZE.

diff --git a/tools/tpm2_nvread.c b/tools/tpm2_nvread.c
index 9d71fd4..251eb5b 100644
--- a/tools/tpm2_nvread.c
+++ b/tools/tpm2_nvread.c
@@ -123,6 +123,9 @@ static bool nv_read(TSS2_SYS_CONTEXT *sapi_context, tpm2_option_flags flags) {
     if (max_data_size > MAX_NV_BUFFER_SIZE) {
         max_data_size = MAX_NV_BUFFER_SIZE;
     }
+    if (max_data_size == 0) {
+        max_data_size = MAX_NV_BUFFER_SIZE;
+    }
 
     UINT8 *data_buffer = malloc(data_size);
     if (!data_buffer) {
diff --git a/tools/tpm2_nvwrite.c b/tools/tpm2_nvwrite.c
index 278e733..14c0b0d 100644
--- a/tools/tpm2_nvwrite.c
+++ b/tools/tpm2_nvwrite.c
@@ -119,6 +119,9 @@ static bool nv_write(TSS2_SYS_CONTEXT *sapi_context) {
     if (max_data_size > MAX_NV_BUFFER_SIZE) {
         max_data_size = MAX_NV_BUFFER_SIZE;
     }
+    if (max_data_size == 0) {
+        max_data_size = MAX_NV_BUFFER_SIZE;
+    }
 
     UINT16 data_offset = 0;
     UINT16 bytes_left = ctx.nv_buffer.t.size;