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Subject[PATCH 44/91] TPM: Zero buffer after copying to userspace
2.6.27-longterm review patch.  If anyone has any objections, please let us know.

------------------

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 files changed, 5 insertions(+), 1 deletions(-)

Index: longterm-2.6.27/drivers/char/tpm/tpm.c
===================================================================
--- longterm-2.6.27.orig/drivers/char/tpm/tpm.c 2012-02-05 22:34:40.951915689 +0100
+++ longterm-2.6.27/drivers/char/tpm/tpm.c 2012-02-05 22:34:41.090914667 +0100
@@ -1069,6 +1069,7 @@
{
struct tpm_chip *chip = file->private_data;
ssize_t ret_size;
+ int rc;

del_singleshot_timer_sync(&chip->user_read_timer);
flush_scheduled_work();
@@ -1079,8 +1080,11 @@
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);
}




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