Re: [PATCH 6.12.y] HID: core: Mitigate potential OOB by removing bogus memset()

[Benjamin Tissoires <bentiss@kernel.org>]

On Jun 03 2026, Wenshan Lan wrote:
> From: Lee Jones <lee@kernel.org>
> 
> [ Upstream commit 0a3fe972a7cb1404f693d6f1711f32bc1d244b1c ]
> 
> 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@kernel.org>
> 
> Signed-off-by: Lee Jones <lee@kernel.org>
> [bentiss: changed the return value]
> Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
> [ Replace hid_warn_ratelimited() with hid_warn() in v6.12. ]
> Signed-off-by: Wenshan Lan <jetlan9@163.com>
> ---

This commit is known for breaking devices. You can't backport this
without the following 3 fixes:
4d3a2a466b8d ("HID: core: Fix size_t specifier in hid_report_raw_event()")
206342541fc8 ("HID: core: introduce hid_safe_input_report()")
2c85c61d1332 ("HID: pass the buffer size to hid_report_raw_event")

Note that this is the same for your 6.6, 6.1 and 5.15 patches.

Cheers,
Benjamin

>  drivers/hid/hid-core.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 294a25330ed0..6d61bf20ec3f 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2029,9 +2029,10 @@ 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(hid, "Event data for report %d was too short (%d vs %d)\n",
> +			 report->id, rsize, csize);
> +		ret = -EINVAL;
> +		goto out;
>  	}
>  
>  	if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_report_event)
> -- 
> 2.43.0
> 
>