From: Norbert Slusarek Date: Sat, 12 Jun 2021 22:18:54 +0200 Subject: [PATCH] can: bcm: fix infoleak in struct bcm_msg_head On 64-bit systems, struct bcm_msg_head has an added padding of 4 bytes between struct members count and ival1. On 32-bit systems, struct bcm_msg_head has an added padding of 4 bytes between struct members nframes and frames[0]. 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") Signed-off-by: Norbert Slusarek Acked-by: Oliver Hartkopp --- net/can/bcm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/can/bcm.c b/net/can/bcm.c index 909b9e684e04..b03062f84fe7 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -402,6 +402,7 @@ static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer) 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 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; @@ -560,6 +562,7 @@ static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer) } /* 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