On Thu, 22 Dec 2022, Philipp Jungkamp wrote:
> Hello,
>
> does this mean the problem lies in 'hid_sensor_custom_probe' itself or
> could this also be caused by local variables in nested functions.
>
> I suspect the problem lies in 'hid_sensor_custom_get_known' where I put
> an instance of 'struct hid_sensor_custom_properties' on the stack.
>
> This struct is way too large (I didn't know there was a upper stack
> limit of 1024). It's current size is sizeof(u16) * 3 *
> HID_CUSTOM_MAX_FEATURE_BYTES = 384.
>
> Would allocating it for the scope of 'hid_sensor_custom_get_known' make
> sense?
>
> Which kind of kernel allocation functions should I use here?
As there was no followup to this as far as I can see, I have just queued
the patch below on top of the hid-sensor branch.
From: Jiri Kosina <jkosina@xxxxxxx>
Subject: [PATCH] HID: hid-sensor-custom: Fix big on-stack allocation in hid_sensor_custom_get_known()
struct hid_sensor_custom_properties is currently 384 bytes big, which consumes
too much stack space for no good reason. Make it dynamically allocated.
Fixes: 98c062e824519 ("HID: hid-sensor-custom: Allow more custom iio sensors")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
drivers/hid/hid-sensor-custom.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/hid/hid-sensor-custom.c b/drivers/hid/hid-sensor-custom.c
index 0c287dde345c..3e3f89e01d81 100644
--- a/drivers/hid/hid-sensor-custom.c
+++ b/drivers/hid/hid-sensor-custom.c
@@ -911,21 +911,28 @@ hid_sensor_custom_get_known(struct hid_sensor_hub_device *hsdev,
int ret;
const struct hid_sensor_custom_match *match =
hid_sensor_custom_known_table;
- struct hid_sensor_custom_properties prop;
+ struct hid_sensor_custom_properties *prop;
- ret = hid_sensor_custom_properties_get(hsdev, &prop);
+ prop = kmalloc(sizeof(struct hid_sensor_custom_properties), GFP_KERNEL);
+ if (!prop)
+ return -ENOMEM;
+
+ ret = hid_sensor_custom_properties_get(hsdev, prop);
if (ret < 0)
- return ret;
+ goto out;
while (match->tag) {
- if (hid_sensor_custom_do_match(hsdev, match, &prop)) {
+ if (hid_sensor_custom_do_match(hsdev, match, prop)) {
*known = match;
- return 0;
+ ret = 0;
+ goto out;
}
match++;
}
-
- return -ENODATA;
+ ret = -ENODATA;
+out:
+ kfree(prop);
+ return ret;
}
static struct platform_device *
--
Jiri Kosina
SUSE Labs
