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    Subject[PATCH 4.14 43/88] can: bcm: fix infoleak in struct bcm_msg_head
    Date
    From: Norbert Slusarek <nslusarek@gmx.net>

    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: ffd980f976e7 ("[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>
    ---
    net/can/bcm.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/net/can/bcm.c b/net/can/bcm.c
    index 12d851c4604d..f691afcc5b8b 100644
    --- a/net/can/bcm.c
    +++ b/net/can/bcm.c
    @@ -406,6 +406,7 @@ 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;
    @@ -453,6 +454,7 @@ static void bcm_rx_changed(struct bcm_op *op, struct canfd_frame *data)
    /* this element is not throttled anymore */
    data->flags &= (BCM_CAN_FLAGS_MASK|RX_RECV);

    + memset(&head, 0, sizeof(head));
    head.opcode = RX_CHANGED;
    head.flags = op->flags;
    head.count = op->count;
    @@ -567,6 +569,7 @@ 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;
    --
    2.30.2
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