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Kernel/ACPI: Map two pages when reading the FADT

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On some cases, the FADT could be on the end of a page, so if we don't
have two pages being mapped, we could easily read from a non-mapped
virtual address, which will trigger the UB sanitizer.

Also, we need to treat the FADT structure as volatile and const, as it
may change at any time, but we should not touch (write) it anyhow.
This commit is contained in:
Liav A
2021-05-08 16:00:28 +03:00
committed by Andreas Kling
parent f7b5352af0
commit 49b132a92d
1 changed files with 4 additions and 2 deletions
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6
Kernel/ACPI/Parser.cpp
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@@ -71,11 +71,13 @@ UNMAP_AFTER_INIT void Parser::init_fadt()
m_fadt = find_table("FACP");
VERIFY(!m_fadt.is_null());
auto sdt = map_typed<Structures::FADT>(m_fadt);
// FIXME: We need at least two pages for mapping, since we can be on the "edge" of one page...
auto sdt = map_typed<const volatile Structures::FADT>(m_fadt, PAGE_SIZE * 2);
dbgln_if(ACPI_DEBUG, "ACPI: FADT @ V{}, {}", &sdt, m_fadt);
dmesgln("ACPI: Fixed ACPI data, Revision {}, length: {} bytes", sdt->h.revision, sdt->h.length);
auto* header = &sdt.ptr()->h;
dmesgln("ACPI: Fixed ACPI data, Revision {}, length: {} bytes", (size_t)header->revision, (size_t)header->length);
dmesgln("ACPI: DSDT {}", PhysicalAddress(sdt->dsdt_ptr));
m_x86_specific_flags.cmos_rtc_not_present = (sdt->ia_pc_boot_arch_flags & (u8)FADTFlags::IA_PC_Flags::CMOS_RTC_Not_Present);