releases/2.6.33.20/tpm-zero-buffer-after-copying-to-userspace.patch

From 3321c07ae5068568cd61ac9f4ba749006a7185c9 Mon Sep 17 00:00:00 2001
From: Peter Huewe <huewe.external.infineon@googlemail.com>
Date: Thu, 15 Sep 2011 14:47:42 -0300
Subject: TPM: Zero buffer after copying to userspace

From: Peter Huewe <huewe.external.infineon@googlemail.com>

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>

---
 drivers/char/tpm/tpm.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1030,6 +1030,7 @@ ssize_t tpm_read(struct file *file, char
 {
 	struct tpm_chip *chip = file->private_data;
 	ssize_t ret_size;
+	int rc;
 
 	del_singleshot_timer_sync(&chip->user_read_timer);
 	flush_scheduled_work();
@@ -1040,8 +1041,11 @@ ssize_t tpm_read(struct file *file, char
 			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);
 	}