[Bug 2037137] Re: shim crashes on arm64 w/ firmware that supports EFI Memory Attribute Protocol

[Heinrich Schuchardt]

*** This bug is a duplicate of bug 2036604 ***
    https://bugs.launchpad.net/bugs/2036604

Hello Dann,

The UEFI specification requires that if a 64 KiB page contains either of

– EfiRuntimeServicesCode
– EfiRuntimeServicesData
– EfiReserved
– EfiACPIMemoryNVS

then all 4KiB pages in the 64KiB page must use identical attributes.

So additionally to the cited patch you must ensure that buffer allocated
with AllocatePages() in handle_image() for which you set memory
attributes does not contain any of the above memory types. The easiest
way to fulfill the requirement is appropriate alignment and rounding of
the used memory. I can't find this in upstream shim.

Best regards

Heinrich

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https://bugs.launchpad.net/bugs/2037137

Title:
  shim crashes on arm64 w/ firmware that supports EFI Memory Attribute
  Protocol

Status in shim package in Ubuntu:
  New

Bug description:
  shim 15.7-0ubuntu1

  qemu-efi-aarch64 now implements EFI Memory Attribute Protocol. When
  shim detects this, it uses it to set memory attributes appropriately
  for the sections of the bootloader image it loads before passing
  control to it. After this change, fresh Ubuntu VMs began crashing on
  startup (bug 2036604):

    --------------------------------------
    BdsDxe: loading Boot0001 "UEFI Misc Device" from PciRoot(0x0)/Pci(0x1,0x3)/Pci(0x0,0x0)
    BdsDxe: starting Boot0001 "UEFI Misc Device" from PciRoot(0x0)/Pci(0x1,0x3)/Pci(0x0,0x0)

    Synchronous Exception at 0x00000000BC300000

    Synchronous Exception at 0x00000000BC300000

    --------------------------------------

   I narrowed this down to only happening when shim executes fbaa64.efi
  (thus the fresh VM). I found upstream shim is unaffected, so I used
  bisection to identify the relevant change:

    From c7b305152802c8db688605654f75e1195def9fd6 Mon Sep 17 00:00:00 2001
    From: Nicholas Bishop <REDACTED>
    Date: Mon, 19 Dec 2022 18:56:13 -0500
    Subject: [PATCH] pe: Align section size up to page size for mem attrs

    Setting memory attributes is generally done at page granularity, and
    this is enforced by checks in `get_mem_attrs` and
    `update_mem_attrs`. But unlike the section address, the section size
    isn't necessarily aligned to 4KiB. Round up the section size to fix
    this.

    Signed-off-by: Nicholas Bishop <nicholasbishop at google.com>

  Please add this patch to shim.

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