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@gmail.com Tested-by: Oliver Hartkopp socketcan@hartkopp.net Signed-off-by: Oliver Hartkopp socketcan@hartkopp.net Cc: linux-stable stable@vger.kernel.org # >= 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) {