Messages in this thread | | | Subject | Re: [PATCHv7 6/7] eeprom: 93xx46: extend driver to plug into the NVMEM framework | From | Vladimir Zapolskiy <> | Date | Thu, 3 Mar 2016 01:18:14 +0200 |
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On 03.03.2016 00:26, Andrew Lunn wrote: >>> 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.
No problem, regmap API from drivers/base/regmap/regmap.c contains all necessary boundary checks as far as I understand.
> 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. >
IMHO to avoid boilerplate code and/or missed/redundant checks it might be better to handle this particular kind of problem only in one common place, for example sysfs binary attribute files do not need this anymore, probably I should scrutinize the situation with this transition to NVMEM as well.
If you remember a reproduction scenario for that crash, please let me know.
At least this changeset must be applied I guess, am I right? In other words is the code without this changeset safe in connection to boundary checks, and this is a new discovered issue?
-- With best wishes, Vladimir
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