[bug report] staging: add bcm2708 vchiq driver

[Dan Carpenter]

Hello popcornmix,

The patch 71bad7f08641: "staging: add bcm2708 vchiq driver" from Jul
2, 2013, leads to the following static checker warning:

	drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:1597 dump_phys_mem()
	error: using offset into zero size array 'pages[]'

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
  1537  static void
  1538  dump_phys_mem(void *virt_addr, uint32_t num_bytes)
  1539  {
  1540          int            rc;
  1541          uint8_t       *end_virt_addr = virt_addr + num_bytes;
  1542          int            num_pages;
  1543          int            offset;
  1544          int            end_offset;
  1545          int            page_idx;
  1546          int            prev_idx;
  1547          struct page   *page;
  1548          struct page  **pages;
  1549          uint8_t       *kmapped_virt_ptr;
  1550  
  1551          /* Align virtAddr and endVirtAddr to 16 byte boundaries. */
  1552  
  1553          virt_addr = (void *)((unsigned long)virt_addr & ~0x0fuL);
  1554          end_virt_addr = (void *)(((unsigned long)end_virt_addr + 15uL) &
  1555                  ~0x0fuL);
  1556  
  1557          offset = (int)(long)virt_addr & (PAGE_SIZE - 1);
  1558          end_offset = (int)(long)end_virt_addr & (PAGE_SIZE - 1);
  1559  
  1560          num_pages = (offset + num_bytes + PAGE_SIZE - 1) / PAGE_SIZE;
  1561  
  1562          pages = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);

The problem that the static checker is complaining about is that
num_pages * sizeof(void *) can overflow to zero leading to an Oops
later.

But really shouldn't we just get rid of this whole function?  Why are
we dumping memory??  I understand that the RPI doesn't have an MMU so we
perhaps don't care too much about security but still...

  1563          if (pages == NULL) {
  1564                  vchiq_log_error(vchiq_arm_log_level,
  1565                          "Unable to allocation memory for %d pages\n",
  1566                          num_pages);
  1567                  return;
  1568          }
  1569  

regards,
dan carpenter