Kyungtae Kim detected a potential integer overflow in bcm_[rx|tx]_setup() when the conversion into ktime multiplies the given value with NSEC_PER_USEC (1000).

Reference: https://marc.info/?l=linux-can&m=154732118819828&w=2

Add a check for the given tv_usec, so that the value stays below one second. Additionally limit the tv_sec value to a reasonable value for CAN related use-cases of 400 days and ensure all values to be positive.

This patch is the pre-4.8 version of upstream commit 93171ba6f1deffd8

Reported-by: Kyungtae Kim kt0755@gmail.com Tested-by: Oliver Hartkopp socketcan@hartkopp.net Signed-off-by: Oliver Hartkopp socketcan@hartkopp.net Cc: linux-stable stable@vger.kernel.org # versions 2.6.26 to 4.7 Tested-by: Kyungtae Kim kt0755@gmail.com Acked-by: Andre Naujoks nautsch2@gmail.com Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- net/can/bcm.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)

diff --git a/net/can/bcm.c b/net/can/bcm.c index 6863310d6973..01d489d0a3de 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -67,6 +67,9 @@ */ #define MAX_NFRAMES 256

+/* limit timers to 400 days for sending/timeouts */ +#define BCM_TIMER_SEC_MAX (400 * 24 * 60 * 60) + /* use of last_frames[index].can_dlc */ #define RX_RECV 0x40 /* received data for this element */ #define RX_THR 0x80 /* element not been sent due to throttle feature */ @@ -136,6 +139,22 @@ static inline ktime_t bcm_timeval_to_ktime(struct bcm_timeval tv) return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC); }

+/* check limitations for timeval provided by user */ +static bool bcm_is_invalid_tv(struct bcm_msg_head *msg_head) +{ + if ((msg_head->ival1.tv_sec < 0) || + (msg_head->ival1.tv_sec > BCM_TIMER_SEC_MAX) || + (msg_head->ival1.tv_usec < 0) || + (msg_head->ival1.tv_usec >= USEC_PER_SEC) || + (msg_head->ival2.tv_sec < 0) || + (msg_head->ival2.tv_sec > BCM_TIMER_SEC_MAX) || + (msg_head->ival2.tv_usec < 0) || + (msg_head->ival2.tv_usec >= USEC_PER_SEC)) + return true; + + return false; +} + #define CFSIZ sizeof(struct can_frame) #define OPSIZ sizeof(struct bcm_op) #define MHSIZ sizeof(struct bcm_msg_head) @@ -846,6 +865,10 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg, if (msg_head->nframes < 1 || msg_head->nframes > MAX_NFRAMES) return -EINVAL;

+ /* check timeval limitations */ + if ((msg_head->flags & SETTIMER) && bcm_is_invalid_tv(msg_head)) + return -EINVAL; + /* check the given can_id */ op = bcm_find_op(&bo->tx_ops, msg_head->can_id, ifindex);

@@ -1011,6 +1034,10 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg, (!(msg_head->can_id & CAN_RTR_FLAG)))) return -EINVAL;

+ /* check timeval limitations */ + if ((msg_head->flags & SETTIMER) && bcm_is_invalid_tv(msg_head)) + return -EINVAL; + /* check the given can_id */ op = bcm_find_op(&bo->rx_ops, msg_head->can_id, ifindex); if (op) {