[PATCH net 7/9] can: netlink: fix CAN XL PWM attribute sizing

[Marc Kleine-Budde <mkl@pengutronix.de>]

From: Zhu Ling <zhuling0805@qq.com>

can_pwm_fill_info() emits the PWM capability limits whenever pwm_const is
present, regardless of whether TMS is enabled. In contrast,
can_pwm_get_size() currently returns 0 when TMS is disabled. It
therefore underestimates the required netlink message size by the nested
attribute header and 6 u32 attributes.

Always account for the PWM capability attributes when pwm_const is present,
and account for the 3 runtime PWM values only when TMS is enabled.

Fixes: 46552323fa67 ("can: netlink: add PWM netlink interface")
Cc: stable@vger.kernel.org
Signed-off-by: Zhu Ling <zhuling0805@qq.com>
Link: https://patch.msgid.link/tencent_9A525E0656A4F7D4CA9CFA1AB1A4BFC6D706@qq.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/bug/linux-3924d490-baed-49dc-880a-6fd1163cf08d
Reviewed-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/netlink.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index c0367c9e65f4..5a3c453a65a7 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -783,7 +783,7 @@ static size_t can_pwm_get_size(const struct can_pwm_const *pwm_const,
 {
 	size_t size;
 
-	if (!pwm_const || !pwm_on)
+	if (!pwm_const)
 		return 0;
 
 	size = nla_total_size(0);			/* nest IFLA_CAN_PWM */
@@ -795,9 +795,11 @@ static size_t can_pwm_get_size(const struct can_pwm_const *pwm_const,
 	size += nla_total_size(sizeof(u32));		/* IFLA_CAN_PWM_PWMO_MIN */
 	size += nla_total_size(sizeof(u32));		/* IFLA_CAN_PWM_PWMO_MAX */
 
-	size += nla_total_size(sizeof(u32));		/* IFLA_CAN_PWM_PWMS */
-	size += nla_total_size(sizeof(u32));		/* IFLA_CAN_PWM_PWML */
-	size += nla_total_size(sizeof(u32));		/* IFLA_CAN_PWM_PWMO */
+	if (pwm_on) {
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_PWM_PWMS */
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_PWM_PWML */
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_PWM_PWMO */
+	}
 
 	return size;
 }
-- 
2.53.0