linux-kernel - Re: add Packet hub driver for Topcliff Platform controller hub

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Date:	Tue, 8 Jan 2013 14:38:51 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Tomoya MORINAGA <tomoya.rohm@...il.com>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: add Packet hub driver for Topcliff Platform controller hub

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@...cle.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
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