[bug report] ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Erik Kaneda,

The patch cefc7ca46235: "ACPI: PRM: implement OperationRegion handler
for the PlatformRtMechanism subtype" from Jun 9, 2021, leads to the
following static checker warning:

	drivers/acpi/prmt.c:113 acpi_parse_prmt()
	error: potential null dereference 'tm'.  (kmalloc returns null)

drivers/acpi/prmt.c
    95  static int __init
    96  acpi_parse_prmt(union acpi_subtable_headers *header, const unsigned long end)
    97  {
    98          struct acpi_prmt_module_info *module_info;
    99          struct acpi_prmt_handler_info *handler_info;
   100          struct prm_handler_info *th;
   101          struct prm_module_info *tm;
   102          u64 mmio_count = 0;
   103          u64 cur_handler = 0;
   104          u32 module_info_size = 0;
   105          u64 mmio_range_size = 0;
   106          void *temp_mmio;
   107  
   108          module_info = (struct acpi_prmt_module_info *) header;
   109          module_info_size = struct_size(tm, handlers, module_info->handler_info_count);
   110          tm = kmalloc(module_info_size, GFP_KERNEL);
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Check for NULL?

   111  
   112          guid_copy(&tm->guid, (guid_t *) module_info->module_guid);
   113          tm->major_rev = module_info->major_rev;
   114          tm->minor_rev = module_info->minor_rev;
   115          tm->handler_count = module_info->handler_info_count;
   116          tm->updatable = true;
   117  
   118          if (module_info->mmio_list_pointer) {
   119                  /*
   120                   * Each module is associated with a list of addr
   121                   * ranges that it can use during the service
   122                   */
   123                  mmio_count = *(u64 *) memremap(module_info->mmio_list_pointer, 8, MEMREMAP_WB);
   124                  mmio_range_size = struct_size(tm->mmio_info, addr_ranges, mmio_count);
   125                  tm->mmio_info = kmalloc(mmio_range_size, GFP_KERNEL);
   126                  temp_mmio = memremap(module_info->mmio_list_pointer, mmio_range_size, MEMREMAP_WB);
   127                  memmove(tm->mmio_info, temp_mmio, mmio_range_size);
   128          } else {
   129                  mmio_range_size = struct_size(tm->mmio_info, addr_ranges, mmio_count);
   130                  tm->mmio_info = kmalloc(mmio_range_size, GFP_KERNEL);
   131                  tm->mmio_info->mmio_count = 0;
   132          }
   133  
   134          INIT_LIST_HEAD(&tm->module_list);
   135          list_add(&tm->module_list, &prm_module_list);

regards,
dan carpenter