From: Dave Young <dyo...@redhat.com> Maniaxx <tripleshift...@gmail.com> reported a kernel boot failure of below: (emulated the panic by using same invalid phys addr in code) There are also a bug in bugzilla.kernel.org: https://bugzilla.kernel.org/show_bug.cgi?id=195633
The reported panic happens after below commit: 7b0a911478c7 efi/x86: Move the EFI BGRT init code to early init code The root cause is the firmware on those machines provides invalid bgrt image addresses. In a kernel before above commit bgrt initializes late and use ioremap to map the image address. Ioremap validate the address, if it is not a valid physical address ioremap just fails and returns. However in current kernel efi bgrt initializes early and uses early_memremap which does not validate the image address, and kernel panic happens. According to ACPI spec the BGRT image address should fall into EFI_BOOT_SERVICES_DATA, see the section 5.2.22.4 of below document: http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf Fix this issue by validating the image address in efi_bgrt_init(). If the image address does not fall into any EFI_BOOT_SERVICES_DATA areas we just bail out. BUG: unable to handle kernel paging request at ffffffffff280001 IP: efi_bgrt_init+0xfb/0x153 ... Call Trace: ? bgrt_init+0xbc/0xbc acpi_parse_bgrt+0xe/0x12 acpi_table_parse+0x89/0xb8 acpi_boot_init+0x445/0x4e2 ? acpi_parse_x2apic+0x79/0x79 ? dmi_ignore_irq0_timer_override+0x33/0x33 setup_arch+0xb63/0xc82 ? early_idt_handler_array+0x120/0x120 start_kernel+0xb7/0x443 ? early_idt_handler_array+0x120/0x120 x86_64_start_reservations+0x29/0x2b x86_64_start_kernel+0x154/0x177 secondary_startup_64+0x9f/0x9f Fixes: 7b0a911478c7 ("efi/x86: Move the EFI BGRT init code to early init code") Reported-by: Maniaxx <tripleshift...@gmail.com> Signed-off-by: Dave Young <dyo...@redhat.com> Cc: Matt Fleming <m...@codeblueprint.co.uk> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> --- drivers/firmware/efi/efi-bgrt.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/efi-bgrt.c b/drivers/firmware/efi/efi-bgrt.c index 8bf27323f7a3..b58233e4ed71 100644 --- a/drivers/firmware/efi/efi-bgrt.c +++ b/drivers/firmware/efi/efi-bgrt.c @@ -27,6 +27,26 @@ struct bmp_header { u32 size; } __packed; +static bool efi_bgrt_addr_valid(u64 addr) +{ + efi_memory_desc_t *md; + + for_each_efi_memory_desc(md) { + u64 size; + u64 end; + + if (md->type != EFI_BOOT_SERVICES_DATA) + continue; + + size = md->num_pages << EFI_PAGE_SHIFT; + end = md->phys_addr + size; + if (addr >= md->phys_addr && addr < end) + return true; + } + + return false; +} + void __init efi_bgrt_init(struct acpi_table_header *table) { void *image; @@ -36,7 +56,7 @@ void __init efi_bgrt_init(struct acpi_table_header *table) if (acpi_disabled) return; - if (!efi_enabled(EFI_BOOT)) + if (!efi_enabled(EFI_MEMMAP)) return; if (table->length < sizeof(bgrt_tab)) { @@ -65,6 +85,10 @@ void __init efi_bgrt_init(struct acpi_table_header *table) goto out; } + if (!efi_bgrt_addr_valid(bgrt->image_address)) { + pr_notice("Ignoring BGRT: invalid image address\n"); + goto out; + } image = early_memremap(bgrt->image_address, sizeof(bmp_header)); if (!image) { pr_notice("Ignoring BGRT: failed to map image header memory\n"); -- 2.9.3
