Commit f638caa2 authored Jun 12, 2021 by Norbert Slusarek Committed by Sasha Levin Jun 30, 2021

can: bcm: fix infoleak in struct bcm_msg_head

commit 5e87ddbe3942e27e939bdc02deb8579b0cbd8ecc upstream.

On 64-bit systems, struct bcm_msg_head has an added padding of 4 bytes between
struct members count and ival1. Even though all struct members are initialized,
the 4-byte hole will contain data from the kernel stack. This patch zeroes out
struct bcm_msg_head before usage, preventing infoleaks to userspace.

Fixes: ffd980f9 ("[CAN]: Add broadcast manager (bcm) protocol")
Link: https://lore.kernel.org/r/trinity-7c1b2e82-e34f-4885-8060-2cd7a13769ce-1623532166177@3c-app-gmx-bs52

Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 959f053a

net/can/bcm.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -392,6 +392,7 @@ static void bcm_tx_timeout_tsklet(unsigned long data)
		if (!op->count && (op->flags & TX_COUNTEVT)) {

		/* create notification to user */
		memset(&msg_head, 0, sizeof(msg_head));
		msg_head.opcode = TX_EXPIRED;
		msg_head.flags = op->flags;
		msg_head.count = op->count;
		@@ -439,6 +440,7 @@ static void bcm_rx_changed(struct bcm_op op, struct can_frame data)
		/* this element is not throttled anymore */
		data->can_dlc &= (BCM_CAN_DLC_MASK\|RX_RECV);

		memset(&head, 0, sizeof(head));
		head.opcode = RX_CHANGED;
		head.flags = op->flags;
		head.count = op->count;
		@@ -550,6 +552,7 @@ static void bcm_rx_timeout_tsklet(unsigned long data)
		struct bcm_msg_head msg_head;

		/* create notification to user */
		memset(&msg_head, 0, sizeof(msg_head));
		msg_head.opcode = RX_TIMEOUT;
		msg_head.flags = op->flags;
		msg_head.count = op->count;