Hi Greg,
On Sun, 2021-11-21 at 13:31 +0100, Greg KH wrote:
> On Sat, Nov 20, 2021 at 03:17:05PM -0800, David E. Box wrote:
> > +static ssize_t registers_read(struct file *filp, struct kobject *kobj,
> > + struct bin_attribute *attr, char *buf, loff_t off,
> > + size_t count)
> > +{
> > + struct device *dev = kobj_to_dev(kobj);
> > + struct sdsi_priv *priv = dev_get_drvdata(dev);
> > + void __iomem *addr = priv->regs_addr;
> > +
> > + memcpy_fromio(buf, addr + off, count);
>
> Oh nice, this will be fun if I provide "interesting" values for off to
> the function right?
>
> Remember:
> All input is evil.
I was relying on sysfs_kf_bin_read() which checks off (pos) before calling us.
if (size) {
if (pos >= size)
return 0;
if (pos + count > size)
count = size - pos;
}
>
> > +
> > + return count;
> > +}
> > +static BIN_ATTR(registers, 0400, registers_read, NULL, SDSI_SIZE_REGS);
> > +
> > +static struct bin_attribute *sdsi_bin_attrs[] = {
> > + &bin_attr_registers,
> > + &bin_attr_state_certificate,
> > + &bin_attr_provision_akc,
> > + &bin_attr_provision_cap,
> > + NULL
> > +};
> > +
> > +static ssize_t guid_show(struct device *dev, struct device_attribute *attr,
> > char *buf)
> > +{
> > + struct sdsi_priv *priv = dev_get_drvdata(dev);
> > +
> > + return sprintf(buf, "0x%x\n", priv->guid);
>
> sysfs_emit() please.
>
> These sysfs attributes are crazy. Who has audited them to be correct
> and work properly? It feels like there are just buffer overflows
> waiting to be exploited in them due to the reading/writing of raw memory
> buffers all over the place.
Agree with the concern. I can submit the tests that were used. Is selftests the
best place?
>
> Where is the userspace tool that uses these files?
The tool will be published in the same github repo as the spec once the driver
is ready.
Thanks.
David
>
> thanks,
>
> greg k-h
