Re: [syzbot] [usb?] WARNING in dib0700_i2c_xfer/usb_submit_urb

Wolfram Sang
2025-03-25T16:59:12Z

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> > > As far as I can tell from the source code, the dib0700 simply isn't able
> > > to handle 0-length reads. Should the dib0700_ctrl_rd() routine be
> > > changed simply to return 0 in such cases?
> >
> > The adapter (I assume the one in dvb-usb-i2c.c) should populate an
> > i2c_adapter_quirks struct with I2C_AQ_NO_ZERO_LEN and then the core will
> > bail out for you.
>
> Or the I2C_AQ_NO_ZERO_LEN_READ flag bit.

Yes, that would be more convervative. Does USB allow zero-length writes?

> What about all the other fields in the i2c_adapter_quirks structure?
> How should they be set? (Note: I don't know anything about this driver
> or these devices; I'm just chasing down the syzbot bug report.)

As I also don't know the hardware, I suggest to leave them empty. 0
means "no quirk".

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