| From 3ab1aff89477dafb1aaeafe8c8669114a02b7226 Mon Sep 17 00:00:00 2001 |
| From: Tim Gardner <tim.gardner@canonical.com> |
| Date: Tue, 6 Dec 2011 11:29:20 -0700 |
| Subject: TPM: Zero buffer whole after copying to userspace |
| |
| From: Tim Gardner <tim.gardner@canonical.com> |
| |
| commit 3ab1aff89477dafb1aaeafe8c8669114a02b7226 upstream. |
| |
| 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 |
| Signed-off-by: Tim Gardner <tim.gardner@canonical.com> |
| Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/char/tpm/tpm.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/char/tpm/tpm.c |
| +++ b/drivers/char/tpm/tpm.c |
| @@ -1115,12 +1115,13 @@ ssize_t tpm_read(struct file *file, char |
| 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; |
| |