[PATCH 4.4 22/65] can: bcm: check timer values before ktime conversion

Greg Kroah-Hartman
2019-02-04T10:41:10Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

commit 93171ba6f1deffd82f381d36cb13177872d023f6 upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/can/bcm.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

--- 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_kti
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)
@@ -855,6 +874,10 @@ static int bcm_tx_setup(struct bcm_msg_h
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);

@@ -1020,6 +1043,10 @@ static int bcm_rx_setup(struct bcm_msg_h
(!(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) {