Re: [RFC v3 1/2] HID: core: Mitigate potential OOB by removing bogus memset()

[Lee Jones]

On Mon, 09 Mar 2026, Lee Jones wrote:

> The memset() in hid_report_raw_event() has the good intention of
> clearing out bogus data by zeroing the area from the end of the incoming
> data string to the assumed end of the buffer.  However, as we have
> previously seen, doing so can easily result in OOB reads and writes in
> the subsequent thread of execution.
> 
> The current suggestion from one of the HID maintainers is to remove the
> memset() and simply return if the incoming event buffer size is not
> large enough to fill the associated report.
> 
> Suggested-by Benjamin Tissoires <bentiss@xxxxxxxxxx>
> Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
> ---
> v2 -> v3: Instead of removing the check entirely, show a warning and return early
> 
> RFC query: Is it better to return SUCCESS or -EINVAL?
> 
>  drivers/hid/hid-core.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index a5b3a8ca2fcb..da9231ca42bc 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2057,9 +2057,9 @@ int hid_report_raw_event(struct hid_device *hid, enum hid_report_type type, u8 *
>  		rsize = max_buffer_size;
>  
>  	if (csize < rsize) {
> -		dbg_hid("report %d is too short, (%d < %d)\n", report->id,
> -				csize, rsize);
> -		memset(cdata + csize, 0, rsize - csize);
> +		hid_warn_ratelimited(hid, "Event data for report %d was too short (%d vs %d)\n",
> +				     report->id, rsize, csize);
> +		goto out;
>  	}
>  
>  	if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_report_event)

Same here.  Are these still in your queue or would you like me to [RESEND]?

-- 
Lee Jones [李琼斯]