Maniaxx reported a kernel boot crash in the EFI code, which I emulated
by using same invalid phys addr in code:
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
There is also a similar bug filed in bugzilla.kernel.org:
https://bugzilla.kernel.org/show_bug.cgi?id=195633
The crash is caused by this commit:
7b0a911478 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 uses ioremap()
to map the image address. Ioremap validates 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 with a warning message.
Reported-by: Maniaxx <tripleshiftone@gmail.com>
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 7b0a911478 ("efi/x86: Move the EFI BGRT init code to early init code")
Link: http://lkml.kernel.org/r/20170609084558.26766-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
792ef14df5