of: Check for phys_addr_t overflows in early_init_dt_add_memory_arch

The common early_init_dt_add_memory_arch takes the base and size
of a memory region as u64 types. The function never checks if
the base and size can actually fit in a phys_addr_t which may
be smaller than 64-bits. This may result in incorrect memory
being passed to memblock_add if the memory falls outside the
range of phys_addr_t. Add range checks for the base and size if
phys_addr_t is smaller than u64.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/fdt.c

@@ -880,6 +880,21 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 	const u64 phys_offset = __pa(PAGE_OFFSET);
 	base &= PAGE_MASK;
 	size &= PAGE_MASK;
+
+	if (sizeof(phys_addr_t) < sizeof(u64)) {
+		if (base > ULONG_MAX) {
+			pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
+					base, base + size);
+			return;
+		}
+
+		if (base + size > ULONG_MAX) {
+			pr_warning("Ignoring memory range 0x%lx - 0x%llx\n",
+					ULONG_MAX, base + size);
+			size = ULONG_MAX - base;
+		}
+	}
+
 	if (base + size < phys_offset) {
 		pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
 			   base, base + size);