[lvc-project] [PATCH net-next] net: usb: aqc111: fix error handling of usbnet read calls

[Andrew Lunn]

On Tue, May 20, 2025 at 02:32:39PM +0300, Nikita Zhandarovich wrote:
> Syzkaller, courtesy of syzbot, identified an error (see report [1]) in
> aqc111 driver, caused by incomplete sanitation of usb read calls'
> results. This problem is quite similar to the one fixed in commit
> 920a9fa27e78 ("net: asix: add proper error handling of usb read errors").
> 
> For instance, usbnet_read_cmd() may read fewer than 'size' bytes,
> even if the caller expected the full amount, and aqc111_read_cmd()
> will not check its result properly. As [1] shows, this may lead
> to MAC address in aqc111_bind() being only partly initialized,
> triggering KMSAN warnings.

It looks like __ax88179_read_cmd() has the same issue? Please could
you have a look around and see if more of the same problem exists.

Are there any use cases where usbnet_read_cmd() can actually return
less than size and it not being an error? Maybe this check for ret !=
size can be moved inside usbnet_read_cmd()?

	Andrew