Kernel: Propagate overflow errors from Memory::page_round_up

Fixes #11402.

1 files changed, 11 insertions, 1 deletions

diff --git a/Kernel/Bus/PCI/Access.cpp b/Kernel/Bus/PCI/Access.cpp
index 09d5e72a1f..183c52fd5e 100644
--- a/Kernel/Bus/PCI/Access.cpp
+++ b/Kernel/Bus/PCI/Access.cpp
@@ -59,7 +59,17 @@ UNMAP_AFTER_INIT bool Access::search_pci_domains_from_acpi_mcfg_table(PhysicalAd
 
     dbgln("PCI: MCFG, length: {}, revision: {}", length, revision);
 
-    auto mcfg_region_or_error = MM.allocate_kernel_region(mcfg_table.page_base(), Memory::page_round_up(length) + PAGE_SIZE, "PCI Parsing MCFG", Memory::Region::Access::ReadWrite);
+    if (Checked<size_t>::addition_would_overflow(length, PAGE_SIZE)) {
+        dbgln("Overflow when adding extra page to allocation of length {}", length);
+        return false;
+    }
+    length += PAGE_SIZE;
+    auto region_size_or_error = Memory::page_round_up(length);
+    if (region_size_or_error.is_error()) {
+        dbgln("Failed to round up length of {} to pages", length);
+        return false;
+    }
+    auto mcfg_region_or_error = MM.allocate_kernel_region(mcfg_table.page_base(), region_size_or_error.value(), "PCI Parsing MCFG", Memory::Region::Access::ReadWrite);
     if (mcfg_region_or_error.is_error())
         return false;
     auto& mcfg = *(ACPI::Structures::MCFG*)mcfg_region_or_error.value()->vaddr().offset(mcfg_table.offset_in_page()).as_ptr();