I really don't know. That's why I'd be hesitant to restrict this. Maybe limit it to something really out of the ordinary, like a year? I am not sure that for example one hour would be out of the question for some edge cases. Maybe someone wants to do a heartbeat for his/her system with a very low priority. This would mean a TX_SETUP with a timeout of an hour and a RX_SETUP with a timeout of a bit more. If the system allow timeouts in those ranges, I think it should be allowed. If someone wants to wait a year for a CAN frame, however unlikely that might be, why not? Andre. On 1/12/19 11:30 PM, Oliver Hartkopp wrote: > Hi Andre, > > just wondered whether it makes sense to limit this value for sending > cyclic messages or for detecting a timeout on reception. > > 4.294.967.295 seconds would be ~136 years - this makes no sense to me > and I would assume someone applied some (unintended?) stuff into the > timeval. > > Don't you think? > > Best, > Oliver > > On 1/12/19 11:16 PM, Andre Naujoks wrote: >> Hi. >> >> The 15 minute limit seems arbitrary to me. I'd be surprised if an >> (R|T)X_SETUP failed because of a timeout greater than this. Are there >> any problems with allowing larger timeouts? If not, I do not see a >> reason to restrict this. >> >> Regards >> Andre >> >> On 1/12/19 10:57 PM, Oliver Hartkopp wrote: >>> 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 15 minutes. >>> >>> Reported-by: Kyungtae Kim <kt0755@xxxxxxxxx> >>> Tested-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> >>> Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> >>> Cc: linux-stable <stable@xxxxxxxxxxxxxxx> # >= 2.6.26 >>> --- >>> net/can/bcm.c | 23 +++++++++++++++++++++++ >>> 1 file changed, 23 insertions(+) >>> >>> diff --git a/net/can/bcm.c b/net/can/bcm.c >>> index 0af8f0db892a..ff3799be077b 100644 >>> --- a/net/can/bcm.c >>> +++ b/net/can/bcm.c >>> @@ -67,6 +67,9 @@ >>> */ >>> #define MAX_NFRAMES 256 >>> +/* limit timers to 15 minutes for sending/timeouts */ >>> +#define BCM_TIMER_SEC_MAX (15*60) >>> + >>> /* use of last_frames[index].flags */ >>> #define RX_RECV 0x40 /* received data for this element */ >>> #define RX_THR 0x80 /* element not been sent due to throttle >>> feature */ >>> @@ -140,6 +143,18 @@ 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 int bcm_is_invalid_tv(struct bcm_msg_head *msg_head) >>> +{ >>> + if ((msg_head->ival1.tv_sec > BCM_TIMER_SEC_MAX) || >>> + (msg_head->ival1.tv_usec >= USEC_PER_SEC) || >>> + (msg_head->ival2.tv_sec > BCM_TIMER_SEC_MAX) || >>> + (msg_head->ival2.tv_usec >= USEC_PER_SEC)) >>> + return 1; >>> + >>> + return 0; >>> +} >>> + >>> #define CFSIZ(flags) ((flags & CAN_FD_FRAME) ? CANFD_MTU : CAN_MTU) >>> #define OPSIZ sizeof(struct bcm_op) >>> #define MHSIZ sizeof(struct bcm_msg_head) >>> @@ -873,6 +888,10 @@ 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, ifindex); >>> if (op) { >>> @@ -1053,6 +1072,10 @@ 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, ifindex); >>> if (op) { >>> >>
