Patch "platform/chrome: cros_ec_dev - double fetch bug in ioctl" has been added to the 4.6-stable tree

[<gregkh@linuxfoundation.org>]

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

    platform/chrome: cros_ec_dev - double fetch bug in ioctl

to the 4.6-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:
     platform-chrome-cros_ec_dev-double-fetch-bug-in-ioctl.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 096cdc6f52225835ff503f987a0d68ef770bb78e Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Tue, 21 Jun 2016 16:58:46 +0300
Subject: platform/chrome: cros_ec_dev - double fetch bug in ioctl

From: Dan Carpenter <dan.carpenter@oracle.com>

commit 096cdc6f52225835ff503f987a0d68ef770bb78e upstream.

We verify "u_cmd.outsize" and "u_cmd.insize" but we need to make sure
that those values have not changed between the two copy_from_user()
calls.  Otherwise it could lead to a buffer overflow.

Additionally, cros_ec_cmd_xfer() can set s_cmd->insize to a lower value.
We should use the new smaller value so we don't copy too much data to
the user.

Reported-by: Pengfei Wang <wpengfeinudt@gmail.com>
Fixes: a841178445bb ('mfd: cros_ec: Use a zero-length array for command data')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/platform/chrome/cros_ec_dev.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/platform/chrome/cros_ec_dev.c
+++ b/drivers/platform/chrome/cros_ec_dev.c
@@ -147,13 +147,19 @@ static long ec_device_ioctl_xcmd(struct
 		goto exit;
 	}
 
+	if (u_cmd.outsize != s_cmd->outsize ||
+	    u_cmd.insize != s_cmd->insize) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
 	s_cmd->command += ec->cmd_offset;
 	ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
 	/* Only copy data to userland if data was received. */
 	if (ret < 0)
 		goto exit;
 
-	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize))
+	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))
 		ret = -EFAULT;
 exit:
 	kfree(s_cmd);


Patches currently in stable-queue which might be from dan.carpenter@oracle.com are

queue-4.6/platform-chrome-cros_ec_dev-double-fetch-bug-in-ioctl.patch