TPM: Zero buffer after copying to userspace
commit 3321c07ae5068568cd61ac9f4ba749006a7185c9 upstream.
Since the buffer might contain security related data it might be a good idea to
zero the buffer after we have copied it to userspace.
This got assigned CVE-2011-1162.
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 9267629..b85ee76 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1055,6 +1055,7 @@
{
struct tpm_chip *chip = file->private_data;
ssize_t ret_size;
+ int rc;
del_singleshot_timer_sync(&chip->user_read_timer);
flush_work_sync(&chip->work);
@@ -1065,8 +1066,11 @@
ret_size = size;
mutex_lock(&chip->buffer_mutex);
- if (copy_to_user(buf, chip->data_buffer, ret_size))
+ rc = copy_to_user(buf, chip->data_buffer, ret_size);
+ memset(chip->data_buffer, 0, ret_size);
+ if (rc)
ret_size = -EFAULT;
+
mutex_unlock(&chip->buffer_mutex);
}