From 2c50ffdc73f3a70d745d249f509fc290754121e6 Mon Sep 17 00:00:00 2001 From: Pengpeng Hou Date: Wed, 15 Jul 2026 16:32:53 +0800 Subject: [PATCH] ACPI: processor: validate MADT IOAPIC entry bounds The IOAPIC hotplug lookup parses both MADT and _MAT records directly. The MADT walk previously used a subtable's declared length to advance the cursor after only locating a generic header. The _MAT path likewise passed a generic header to the IOAPIC helper. Validate that a current record has a complete generic header, that its declared length is contained in the available record range, and that a typed IOAPIC record contains the full fixed IOAPIC body before reading its fields. Use the same relation for both MADT and _MAT provider paths. Fixes: ecf5636dcd59 ("ACPI: Add interfaces to parse IOAPIC ID for IOAPIC hotplug") Signed-off-by: Pengpeng Hou Link: https://patch.msgid.link/20260715083253.22831-1-pengpeng@iscas.ac.cn Signed-off-by: Rafael J. Wysocki --- drivers/acpi/processor_core.c | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c index a4498357bd16..3bf076c150fa 100644 --- a/drivers/acpi/processor_core.c +++ b/drivers/acpi/processor_core.c @@ -336,11 +336,26 @@ int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id) EXPORT_SYMBOL_GPL(acpi_get_cpuid); #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC -static int get_ioapic_id(struct acpi_subtable_header *entry, u32 gsi_base, +static bool madt_entry_is_valid(struct acpi_subtable_header *entry, + unsigned long end) +{ + unsigned long start = (unsigned long)entry; + + if (start >= end || end - start < sizeof(*entry)) + return false; + + return entry->length >= sizeof(*entry) && entry->length <= end - start; +} + +static int get_ioapic_id(struct acpi_subtable_header *entry, + const unsigned long end, u32 gsi_base, u64 *phys_addr, int *ioapic_id) { struct acpi_madt_io_apic *ioapic = (struct acpi_madt_io_apic *)entry; + if (!madt_entry_is_valid(entry, end) || BAD_MADT_ENTRY(ioapic, end)) + return 0; + if (ioapic->global_irq_base != gsi_base) return 0; @@ -361,17 +376,19 @@ static int parse_madt_ioapic_entry(u32 gsi_base, u64 *phys_addr) return apic_id; entry = (unsigned long)madt; + if (madt->header.length < sizeof(*madt)) + return apic_id; madt_end = entry + madt->header.length; /* Parse all entries looking for a match. */ entry += sizeof(struct acpi_table_madt); - while (entry + sizeof(struct acpi_subtable_header) < madt_end) { + while (madt_entry_is_valid((struct acpi_subtable_header *)entry, + madt_end)) { hdr = (struct acpi_subtable_header *)entry; if (hdr->type == ACPI_MADT_TYPE_IO_APIC && - get_ioapic_id(hdr, gsi_base, phys_addr, &apic_id)) + get_ioapic_id(hdr, madt_end, gsi_base, phys_addr, &apic_id)) break; - else - entry += hdr->length; + entry += hdr->length; } return apic_id; @@ -398,7 +415,9 @@ static int parse_mat_ioapic_entry(acpi_handle handle, u32 gsi_base, header = (struct acpi_subtable_header *)obj->buffer.pointer; if (header->type == ACPI_MADT_TYPE_IO_APIC) - get_ioapic_id(header, gsi_base, phys_addr, &apic_id); + get_ioapic_id(header, + (unsigned long)header + obj->buffer.length, + gsi_base, phys_addr, &apic_id); exit: kfree(buffer.pointer);