Re: [PATCH] HID: usbhid: fix recurrent out-of-bounds bug in usbhid_parse()

[Nikita Zhandarovich]

Hi,

On 6/4/24 07:15, Jiri Kosina wrote:
> On Tue, 4 Jun 2024, Kees Cook wrote:
> 
>> This isn't the right solution. The problem is that hid_class_descriptor 
>> is a flexible array but was sized as a single element fake flexible 
>> array:
>>
>> struct hid_descriptor {
>> 	   __u8  bLength;
>> 	   __u8  bDescriptorType;
>> 	   __le16 bcdHID;
>> 	   __u8  bCountryCode;
>> 	   __u8  bNumDescriptors;
>>
>> 	   struct hid_class_descriptor desc[1];
>> } __attribute__ ((packed));
>>
>> This likely needs to be: 
>>
>> struct hid_class_descriptor desc[] __counted_by(bNumDescriptors);
>>
>> And then check for any sizeof() uses of the struct that might have changed.
> 
> Ah, you are of course right, not sure what I was thinking. Thanks a lot 
> for catching my brainfart.
> 
> I am dropping the patch for now; Nikita, will you please send a refreshed 
> one?
> 

Thanks for catching my mistake.

I'll gladly send a revised version, hoping to do it very soon.

Regards,
Nikita