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x86/efi: Check status field to validate BGRT header 

Madper reported seeing the following crash,

  BUG: unable to handle kernel paging request at ffffffffff340003
  IP: [<ffffffff81d85ba4>] efi_bgrt_init+0x9d/0x133
  Call Trace:
   [<ffffffff81d8525d>] efi_late_init+0x9/0xb
   [<ffffffff81d68f59>] start_kernel+0x436/0x450
   [<ffffffff81d6892c>] ? repair_env_string+0x5c/0x5c
   [<ffffffff81d68120>] ? early_idt_handlers+0x120/0x120
   [<ffffffff81d685de>] x86_64_start_reservations+0x2a/0x2c
   [<ffffffff81d6871e>] x86_64_start_kernel+0x13e/0x14d

This is caused because the layout of the ACPI BGRT header on this system
doesn't match the definition from the ACPI spec, and so we get a bogus
physical address when dereferencing ->image_address in efi_bgrt_init().

Luckily the status field in the BGRT header clearly marks it as invalid,
so we can check that field and skip BGRT initialisation.

Reported-by: Madper Xie <cxie@redhat.com>
Suggested-by: Toshi Kani <toshi.kani@hp.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
This commit is contained in:
Matt Fleming 2014-02-13 17:17:54 +00:00
parent c55d016f7a
commit 09503379dc
1 changed files with 1 additions and 1 deletions
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2
arch/x86/platform/efi/efi-bgrt.c
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@ -42,7 +42,7 @@ void __init efi_bgrt_init(void)
if (bgrt_tab->header.length < sizeof(*bgrt_tab)) if (bgrt_tab->header.length < sizeof(*bgrt_tab))
return; return;
if (bgrt_tab->version != 1) if (bgrt_tab->version != 1 || bgrt_tab->status != 1)
return; return;
if (bgrt_tab->image_type != 0 || !bgrt_tab->image_address) if (bgrt_tab->image_type != 0 || !bgrt_tab->image_address)
return; return;