Re: [PATCH] HID: core: downgrade short report warning to debug level

[Benjamin Tissoires <bentiss@kernel.org>]

On Apr 14 2026, Oleksandr Natalenko wrote:
> Hello.
> 
> Thank you for the submission. Please see comments inline.
> 
> On úterý 14. dubna 2026 23:41:43, středoevropský letní čas Anj Duvnjak wrote:
> > Commit 0a3fe972a7cb ("HID: core: Mitigate potential OOB by removing bogus
> > memset()") replaced the silent memset() with hid_warn_ratelimited(), which
> > causes dmesg flooding on devices that legitimately send short reports,
> > such as the APC UPS (051D:0002).
> > 
> > Downgrade to dbg_hid() to restore the previous behaviour of only
> > reporting under HID_DEBUG, while preserving the security fix of
> > removing the bogus memset().
> > 
> > Reported-by: Anj Duvnjak <avian@extremenerds.net>
> > Closes: https://lore.kernel.org/linux-input/MW5PR84MB135613E7947113897DD9FDA4C7272@MW5PR84MB1356.NAMPRD84.PROD.OUTLOOK.COM/
> > Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > Closes: https://lore.kernel.org/linux-input/6256259.lOV4Wx5bFT@natalenko.name/
> 
> I think these Closes: should be Link: instead. And probably Fixes: should be added as follows:
> 
> Fixes: 0a3fe972a7cb14 ("HID: core: Mitigate potential OOB by removing bogus memset()")
> 
> > Signed-off-by: Anj Duvnjak <avian@extremenerds.net>
> > ---
> >  drivers/hid/hid-core.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> > index 833df14ef68f..de8a179347ec 100644
> > --- a/drivers/hid/hid-core.c
> > +++ b/drivers/hid/hid-core.c
> > @@ -2057,8 +2057,8 @@ int hid_report_raw_event(struct hid_device *hid, enum hid_report_type type, u8 *
> >  		rsize = max_buffer_size;
> >  
> >  	if (csize < rsize) {
> > -		hid_warn_ratelimited(hid, "Event data for report %d was too short (%d vs %d)\n",
> > -				     report->id, rsize, csize);
> > +		dbg_hid("Event data for report %d was too short (%d vs %d)\n",
> > +			report->id, rsize, csize);
> 
> Ratelimiting is good to keep, IMO. There's a separate macro for that, hid_dbg_ratelimited(), which is surprisingly not used anywhere at the moment as far as I can grep, but it should do the job.

Thanks for the bug and the review.

However, I've got a proper fix which restores the original behavior
while still preventing the OOWM write. It should be out today or
tomorrow.

Cheers,
Benjamin

> 
> >  		ret = -EINVAL;
> >  		goto out;
> >  	}
> > 
> 
> 
> -- 
> Oleksandr Natalenko, MSE