Re: [PATCHv7 6/7] eeprom: 93xx46: extend driver to plug into the NVMEM framework

Andrew Lunn
2016-03-02T22:26:44Z

> > static ssize_t
> > -eeprom_93xx46_bin_read(struct file *filp, struct kobject *kobj,
> > - struct bin_attribute *bin_attr,
> > - char *buf, loff_t off, size_t count)
> > +eeprom_93xx46_read(struct eeprom_93xx46_dev *edev, char *buf,
> > + unsigned off, size_t count)
> > {
> > - struct eeprom_93xx46_dev *edev;
> > - struct device *dev;
> > ssize_t ret = 0;
> >
> > - dev = kobj_to_dev(kobj);
> > - edev = dev_get_drvdata(dev);
> > + if (unlikely(off >= edev->size))
> > + return 0;
> > + if ((off + count) > edev->size)
> > + count = edev->size - off;
> > + if (unlikely(!count))
> > + return count;
> >
>
> I'm scratching my head, do you want to kind of revert
> the change https://lkml.org/lkml/2015/7/26/89 ? Why?

Hi Vladimir

I had not noticed you had removed this.

> If you know regmap_config.max_register, then all necessary
> boundary checks can be done inside NVMEM core.

You don't have to use NVMEM, you could use the regmap directly. It is
a public API. Also, during implementation, i did manage to get out of
bounds read passed into the drivers and they caused a crash. That
might of been AT24, i don't remember, but verifying is better than
possible crashing.

> > +/*
> > + * Provide a regmap interface, which is registered with the NVMEM
> > + * framework
> > +*/
> > +static int eeprom_93xx46_regmap_read(void *context, const void *reg,
> > + size_t reg_size, void *val,
> > + size_t val_size)
> > +{
> > + struct eeprom_93xx46_dev *eeprom_93xx46 = context;
> > + off_t offset = *(u32 *)reg;
> > + int err;
> > +
> > + err = eeprom_93xx46_read(eeprom_93xx46, val, offset, val_size);
> > + if (err)
> > + return err;
> > + return 0;
>
> return eeprom_93xx46_read(eeprom_93xx46, val, offset, val_size);

As i've said a few times now to a few different people reviewing these
patches, regmap wants either an error code or 0.

Andrew