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    efi: Fix boot panic because of invalid BGRT image address · 792ef14d
    Dave Young 提交于
    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:
    
      7b0a9114 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: NManiaxx <tripleshiftone@gmail.com>
    Signed-off-by: NDave Young <dyoung@redhat.com>
    Signed-off-by: NArd 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: 7b0a9114 ("efi/x86: Move the EFI BGRT init code to early init code")
    Link: http://lkml.kernel.org/r/20170609084558.26766-2-ard.biesheuvel@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
    792ef14d
efi-bgrt.c 2.6 KB