re: add Packet hub driver for Topcliff Platform controller hub

Dan Carpenter
2013-01-07T09:02:25Z

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.