Patch "tpm-dev-common: Reject too short writes" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

tpm-dev-common: Reject too short writes

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tpm-dev-common-reject-too-short-writes.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alexander Steffen <[email protected]>
Date: Fri, 8 Sep 2017 17:21:32 +0200
Subject: tpm-dev-common: Reject too short writes

From: Alexander Steffen <[email protected]>

commit ee70bc1e7b63ac8023c9ff9475d8741e397316e7 upstream.

tpm_transmit() does not offer an explicit interface to indicate the number of valid bytes in the communication buffer. Instead, it relies on the commandSize field in the TPM header that is encoded within the buffer. Therefore, ensure that a) enough data has been written to the buffer, so that the commandSize field is present and b) the commandSize field does not announce more data than has been written to the buffer.

This should have been fixed with CVE-2011-1161 long ago, but apparently a correct version of that patch never made it into the kernel.

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

@@ -110,6 +110,12 @@ ssize_t tpm_common_write(struct file *fi
 		return -EFAULT;
 	}
 
+	if (in_size < 6 ||
+	    in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) {
+		mutex_unlock(&priv->buffer_mutex);
+		return -EINVAL;
+	}
+
 	/* atomic tpm command send and result receive. We only hold the ops
 	 * lock during this period so that the tpm can be unregistered even if
 	 * the char dev is held open.

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/tpm-dev-common-reject-too-short-writes.patch