of/irq: Prevent device address out-of-bounds read in interrupt map walk

When of_irq_parse_raw() is invoked with a device address smaller than
the interrupt parent node (from #address-cells property), KASAN detects
the following out-of-bounds read when populating the initial match table
(dyndbg="func of_irq_parse_* +p"):

  OF: of_irq_parse_one: dev=/soc@0/picasso/watchdog, index=0
  OF:  parent=/soc@0/pci@878000000000/gpio0@17,0, intsize=2
  OF:  intspec=4
  OF: of_irq_parse_raw: ipar=/soc@0/pci@878000000000/gpio0@17,0, size=2
  OF:  -> addrsize=3
  ==================================================================
  BUG: KASAN: slab-out-of-bounds in of_irq_parse_raw+0x2b8/0x8d0
  Read of size 4 at addr ffffff81beca5608 by task bash/764

  CPU: 1 PID: 764 Comm: bash Tainted: G           O       6.1.67-484c613561-nokia_sm_arm64 #1
  Hardware name: Unknown Unknown Product/Unknown Product, BIOS 2023.01-12.24.03-dirty 01/01/2023
  Call trace:
   dump_backtrace+0xdc/0x130
   show_stack+0x1c/0x30
   dump_stack_lvl+0x6c/0x84
   print_report+0x150/0x448
   kasan_report+0x98/0x140
   __asan_load4+0x78/0xa0
   of_irq_parse_raw+0x2b8/0x8d0
   of_irq_parse_one+0x24c/0x270
   parse_interrupts+0xc0/0x120
   of_fwnode_add_links+0x100/0x2d0
   fw_devlink_parse_fwtree+0x64/0xc0
   device_add+0xb38/0xc30
   of_device_add+0x64/0x90
   of_platform_device_create_pdata+0xd0/0x170
   of_platform_bus_create+0x244/0x600
   of_platform_notify+0x1b0/0x254
   blocking_notifier_call_chain+0x9c/0xd0
   __of_changeset_entry_notify+0x1b8/0x230
   __of_changeset_apply_notify+0x54/0xe4
   of_overlay_fdt_apply+0xc04/0xd94
   ...

  The buggy address belongs to the object at ffffff81beca5600
   which belongs to the cache kmalloc-128 of size 128
  The buggy address is located 8 bytes inside of
   128-byte region [ffffff81beca5600, ffffff81beca5680)

  The buggy address belongs to the physical page:
  page:00000000230d3d03 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1beca4
  head:00000000230d3d03 order:1 compound_mapcount:0 compound_pincount:0
  flags: 0x8000000000010200(slab|head|zone=2)
  raw: 8000000000010200 0000000000000000 dead000000000122 ffffff810000c300
  raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   ffffff81beca5500: 04 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
   ffffff81beca5580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  >ffffff81beca5600: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                        ^
   ffffff81beca5680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
   ffffff81beca5700: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
  ==================================================================
  OF:  -> got it !

Prevent the out-of-bounds read by copying the device address into a
buffer of sufficient size.

Signed-off-by: Stefan Wiehler <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Herring (Arm) <[email protected]>

Author: sephalon

drivers/of/irq.c

@@ -344,7 +344,8 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
 	struct device_node *p;
 	const __be32 *addr;
 	u32 intsize;
-	int i, res;
+	int i, res, addr_len;
+	__be32 addr_buf[3] = { 0 };
 
 	pr_debug("of_irq_parse_one: dev=%pOF, index=%d\n", device, index);
 
@@ -353,13 +354,19 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
 		return of_irq_parse_oldworld(device, index, out_irq);
 
 	/* Get the reg property (if any) */
-	addr = of_get_property(device, "reg", NULL);
+	addr = of_get_property(device, "reg", &addr_len);
+
+	/* Prevent out-of-bounds read in case of longer interrupt parent address size */
+	if (addr_len > (3 * sizeof(__be32)))
+		addr_len = 3 * sizeof(__be32);
+	if (addr)
+		memcpy(addr_buf, addr, addr_len);
 
 	/* Try the new-style interrupts-extended first */
 	res = of_parse_phandle_with_args(device, "interrupts-extended",
 					"#interrupt-cells", index, out_irq);
 	if (!res)
-		return of_irq_parse_raw(addr, out_irq);
+		return of_irq_parse_raw(addr_buf, out_irq);
 
 	/* Look for the interrupt parent. */
 	p = of_irq_find_parent(device);
@@ -389,7 +396,7 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
 
 
 	/* Check if there are any interrupt-map translations to process */
-	res = of_irq_parse_raw(addr, out_irq);
+	res = of_irq_parse_raw(addr_buf, out_irq);
  out:
 	of_node_put(p);
 	return res;