[hardy CVE 1/1] TPM: Zero buffer after copying to userspace

Andy Whitcroft apw at canonical.com
Mon Dec 5 16:18:40 UTC 2011

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

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 at linux.vnet.ibm.com>
Cc: Stable Kernel <stable at kernel.org>
Signed-off-by: James Morris <jmorris at namei.org>

(backported from commit 3321c07ae5068568cd61ac9f4ba749006a7185c9)
BugLink: http://bugs.launchpad.net/bugs/899463
Signed-off-by: Andy Whitcroft <apw at canonical.com>
 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;
@@ -1007,8 +1008,11 @@ ssize_t tpm_read(struct file *file, char __user *buf,
 			ret_size = size;
-		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;

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