1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 32362cf35b8d..ad7c7320dd1b 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1221,12 +1221,13 @@ ssize_t tpm_read(struct file *file, char __user *buf,
         ret_size = atomic_read(&chip->data_pending);
         atomic_set(&chip->data_pending, 0);
         if (ret_size > 0) {     /* relay data */
+                ssize_t orig_ret_size = ret_size;
                 if (size < ret_size)
                         ret_size = size;
 
                 mutex_lock(&chip->buffer_mutex);
                 rc = copy_to_user(buf, chip->data_buffer, ret_size);
-                memset(chip->data_buffer, 0, ret_size);
+                memset(chip->data_buffer, 0, orig_ret_size);
                 if (rc)
                         ret_size = -EFAULT;