TPM: Zero buffer whole after copying to userspace
Commit 3321c07ae5068568cd61ac9f4ba749006a7185c9 correctly clears the TPM
buffer if the user specified read length is >= the TPM buffer length. However,
if the user specified read length is < the TPM buffer length, then part of the
TPM buffer is left uncleared.
Reported-by: Seth Forshee <seth.forshee@canonical.com>
Cc: Debora Velarde <debora@linux.vnet.ibm.com>
Cc: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Cc: Marcel Selhorst <m.selhorst@sirrix.com>
Cc: tpmdd-devel@lists.sourceforge.net
Cc: stable@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 32362cf..ad7c732 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1221,12 +1221,13 @@
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;