From patchwork Mon Dec 5 16:18:40 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [hardy,CVE,1/1] TPM: Zero buffer after copying to userspace From: Andy Whitcroft X-Patchwork-Id: 129346 Message-Id: <1323101922-9653-2-git-send-email-apw@canonical.com> To: kernel-team@lists.ubuntu.com Cc: Andy Whitcroft Date: Mon, 5 Dec 2011 16:18:40 +0000 From: Peter Huewe 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 Cc: Stable Kernel Signed-off-by: James Morris (backported from commit 3321c07ae5068568cd61ac9f4ba749006a7185c9) CVE-2011-1162 BugLink: http://bugs.launchpad.net/bugs/899463 Signed-off-by: Andy Whitcroft --- drivers/char/tpm/tpm.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c index 14ad745..27dd72d 100644 --- a/drivers/char/tpm/tpm.c +++ b/drivers/char/tpm/tpm.c @@ -997,6 +997,7 @@ ssize_t tpm_read(struct file *file, char __user *buf, { struct tpm_chip *chip = file->private_data; int ret_size; + int rc; del_singleshot_timer_sync(&chip->user_read_timer); flush_scheduled_work(); @@ -1007,8 +1008,11 @@ ssize_t tpm_read(struct file *file, char __user *buf, 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); }