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

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Date:	Mon, 7 Jan 2013 12:02:10 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	masa-korg@....okisemi.com
Cc:	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org,
	Tomoya MORINAGA <tomoya.rohm@...il.com>
Subject: re: add Packet hub driver for Topcliff Platform controller hub

Hi Masayuki Ohtak,

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.

regards,
dan carpenter

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