Commit 9b1087aa authored Jan 05, 2015 by Oliver Hartkopp Committed by Marc Kleine-Budde Jan 15, 2015

can: dev: fix crtlmode_supported check

When changing flags in the CAN drivers ctrlmode the provided new content has to
be checked whether the bits are allowed to be changed. The bits that are to be
changed are given as a bitfield in cm->mask. Therefore checking against
cm->flags is wrong as the content can hold any kind of values.

The iproute2 tool sets the bits in cm->mask and cm->flags depending on the
detected command line options. To be robust against bogus user space
applications additionally sanitize the provided flags with the provided mask.

Cc: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

parent 870482a4

drivers/net/can/dev.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -807,10 +807,14 @@ static int can_changelink(struct net_device *dev,
		if (dev->flags & IFF_UP)
		return -EBUSY;
		cm = nla_data(data[IFLA_CAN_CTRLMODE]);
		if (cm->flags & ~priv->ctrlmode_supported)

		/* check whether changed bits are allowed to be modified */
		if (cm->mask & ~priv->ctrlmode_supported)
		return -EOPNOTSUPP;

		/* clear bits to be modified and copy the flag values */
		priv->ctrlmode &= ~cm->mask;
		priv->ctrlmode \|= cm->flags;
		priv->ctrlmode \|= (cm->flags & cm->mask);

		/* CAN_CTRLMODE_FD can only be set when driver supports FD */
		if (priv->ctrlmode & CAN_CTRLMODE_FD)

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