[PATCH v3 04/10] hw/tpm: tis: Only read from response buffer if rw_offset < len

[Stefan Berger <stefanb@linux.ibm.com>]

Only read a byte from the response buffer, if the rw_offset < len.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 hw/tpm/tpm_tis_common.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/tpm/tpm_tis_common.c b/hw/tpm/tpm_tis_common.c
index a134d5c205..4ba228116b 100644
--- a/hw/tpm/tpm_tis_common.c
+++ b/hw/tpm/tpm_tis_common.c
@@ -273,13 +273,15 @@ static uint32_t tpm_tis_data_read(TPMState *s, uint8_t locty)
         len = MIN(tpm_cmd_get_size(&s->buffer),
                   s->be_buffer_size);
 
-        ret = s->buffer[s->rw_offset++];
+        if (s->rw_offset < len) {
+            ret = s->buffer[s->rw_offset++];
+            trace_tpm_tis_data_read(ret, s->rw_offset - 1);
+        }
         if (s->rw_offset >= len) {
             /* got last byte */
             tpm_tis_sts_set(&s->loc[locty], TPM_TIS_STS_VALID);
             tpm_tis_raise_irq(s, locty, TPM_TIS_INT_STS_VALID);
         }
-        trace_tpm_tis_data_read(ret, s->rw_offset - 1);
     }
 
     return ret;
-- 
2.55.0