Re: [PATCH] USB: core: Use `krealloc()` in `usb_cache_string()`

["Bence Csókás" <bence98@sch.bme.hu>]

On 3/15/26 10:59, Bence Csókás wrote:
> Hi,
> 
> On 3/15/26 10:47, Greg Kroah-Hartman wrote:
>> On Sun, Mar 15, 2026 at 10:40:48AM +0100, Bence Csókás wrote:
>>>> Also, how was this tested?
>>>
>>> I just compiled and booted it on my Arch box (with the original vendor
>>> config), an AthlonII X2 PC. I'm now typing this mail on a USB 
>>> keyboard and
>>> mouse under Plasma, running this kernel :) I also plugged in a pendrive,
>>> mounted it, `ls`'d the mount, unmounted, unplugged, and did this 2 more
>>> times.
>>>
>>> I realize I should probably put this info under the dashes. I'll 
>>> prepare a
>>> v2.
>>
>> Try looking at the USB strings in the device, as that's the path here
>> that is exercised.  Just using the device doesn't actually grab them
>> from the descriptor table.
> 
> Sure.
> 
>    $ sudo lsusb -vvv | grep iProduct
>    can't get debug descriptor: Resource temporarily unavailable
>      iProduct                2 OHCI PCI host controller
>      iProduct                2 HP USB Smart Card Keyboard
>    can't get device qualifier: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>      iProduct                2 USB OPTICAL MOUSE
>    can't get debug descriptor: Resource temporarily unavailable
>    can't get device qualifier: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>      iProduct                2 EHCI Host Controller
>      iProduct                2 EHCI Host Controller
>    can't get device qualifier: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>      iProduct                2 Disk 2.0
>      iProduct                2 EHCI Host Controller
>    can't get device qualifier: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>      iProduct                2 OHCI PCI host controller
>      iProduct                2 OHCI PCI host controller
>    can't get debug descriptor: Resource temporarily unavailable
>    can't get debug descriptor: Resource temporarily unavailable
>      iProduct                2 OHCI PCI host controller
> 
> Are these -EAGAINs cause for concern?

It happens with the vendor kernel (6.19.8-arch1-1) too, so it's probably 
just some weirdness in my HW...

>> And sorry for the extra review, I'm a bit picky about this function, it
>> was my first contribution to Linux way back in 1999 or so, and happen to
>> know too much about USB descriptor strings :)
> 
> A good review is a thorough review.
> 
>> thanks,
>>
>> greg k-h
>>
> 
> Bence