Re: add Packet hub driver for Topcliff Platform controller hub

Dan Carpenter
2013-01-08T11:39:05Z

On Tue, Jan 08, 2013 at 07:30:34PM +0900, Tomoya MORINAGA wrote:
> Hi Dan,
>
> On Mon, Jan 7, 2013 at 6:02 PM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > The patch cf4ece53460c: "add Packet hub driver for Topcliff Platform
> > controller hub" from Sep 1, 2010, leads to the following warning:
> > drivers/misc/pch_phub.c:596 pch_phub_bin_write()
> > error: buffer overflow 'buf' 4096 <= 15359
> >
> > Sorry my question is about an old patch. Smatch complains because we
> > only pass a PAGE_SIZE buffer to sysfs files so the test for
> > "if (count > PCH_PHUB_OROM_SIZE) {" makes it think we are overflowing.
> > In fact, count is never more than 4096 so there is no overflow, but I
> > also think that it means only the first 4096 bytes of the firmware gets
> > updated.
> >
> > drivers/misc/pch_phub.c
> > 560 static ssize_t pch_phub_bin_write(struct file *filp, struct kobject *kobj,
> > 561 struct bin_attribute *attr,
> > 562 char *buf, loff_t off, size_t count)
> > 563 {
> > 564 int err;
> > 565 unsigned int addr_offset;
> > 566 int ret;
> > 567 ssize_t rom_size;
> > 568 struct pch_phub_reg *chip =
> > 569 dev_get_drvdata(container_of(kobj, struct device, kobj));
> > 570
> > 571 ret = mutex_lock_interruptible(&pch_phub_mutex);
> > 572 if (ret)
> > 573 return -ERESTARTSYS;
> > 574
> > 575 if (off > PCH_PHUB_OROM_SIZE) {
> > 576 addr_offset = 0;
> > 577 goto return_ok;
> > 578 }
> > 579 if (count > PCH_PHUB_OROM_SIZE) {
> > ^^^^^^^^^^^^^^^^^^
> > This is 15359.
> >
> > 580 addr_offset = 0;
> > 581 goto return_ok;
> > 582 }
> > 583
> > 584 chip->pch_phub_extrom_base_address = pci_map_rom(chip->pdev, &rom_size);
> > 585 if (!chip->pch_phub_extrom_base_address) {
> > 586 err = -ENOMEM;
> > 587 goto exrom_map_err;
> > 588 }
> > 589
> > 590 for (addr_offset = 0; addr_offset < count; addr_offset++) {
> > 591 if (PCH_PHUB_OROM_SIZE < off + addr_offset)
> > 592 goto return_ok;
> > 593
> > 594 ret = pch_phub_write_serial_rom(chip,
> > 595 chip->pch_opt_rom_start_address + addr_offset + off,
> > 596 buf[addr_offset]);
> > ^^^^^^^^^^^^^^^^
> > Smatch complains because "buf" is only 4096 bytes.
> >
>
> I can understand your saying.
>
> You mean just delete the following condition ?
>
> 579 if (count > PCH_PHUB_OROM_SIZE) {
>

What I'm saying is that sysfs files can only be 4096 bytes (larger
on some arches with a larger PAGE_SIZE) and your firmware is larger
than that. It won't work.

regards,
dan carpenter

> Thanks.
>
> --
> ROHM Co., Ltd.
> tomoya