From: Norbert Slusarek <nslusarek@gmx.net> mainline inclusion from mainline-v5.13-rc7 commit 5e87ddbe3942e27e939bdc02deb8579b0cbd8ecc category: bugfix bugzilla: NA CVE: CVE-2021-34693 -------------------------------- 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-16235... 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: Yang Yingliang <yangyingliang@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Reviewed-by: Yue Haibing <yuehaibing@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- net/can/bcm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/can/bcm.c b/net/can/bcm.c index f5f97d9c17d20..0f09838ebef6e 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -393,6 +393,7 @@ 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; @@ -440,6 +441,7 @@ 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; @@ -554,6 +556,7 @@ 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; -- 2.25.1