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Dave Young 792ef14df5 efi: Fix boot panic because of invalid BGRT image address 
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>
2017-06-09 14:50:11 +02:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-06 14:30:17 -07:00
block block: Avoid that blk_exit_rl() triggers a use-after-free 2017-06-01 13:07:55 -06:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto crypto: gcm - wait for crypto op not signal safe 2017-05-23 12:45:11 +08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-06 14:30:17 -07:00
drivers efi: Fix boot panic because of invalid BGRT image address 2017-06-09 14:50:11 +02:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs fs/ufs: Set UFS default maximum bytes per file 2017-06-04 16:33:54 -07:00
include Power management fixes for v4.12-rc5 2017-06-08 17:40:32 -07:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel Power management fixes for v4.12-rc5 2017-06-08 17:40:32 -07:00
lib test_bpf: Add a couple of tests for BPF_JSGE. 2017-05-25 14:37:56 -04:00
mm mm: consider memblock reservations for deferred memory initialization sizing 2017-06-02 15:07:38 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-06 14:30:17 -07:00
samples samples/bpf: run cleanup routines when receiving SIGTERM 2017-05-11 21:43:30 -04:00
scripts scripts/gdb: make lx-dmesg command work (reliably) 2017-06-02 15:07:38 -07:00
security Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
sound sound fixes for 4.12-rc4 2017-06-02 09:40:47 -07:00
tools powerpc fixes for 4.12 #4 2017-05-27 09:28:34 -07:00
usr initramfs: fix disabling of initramfs (and its compression) 2017-06-02 15:07:37 -07:00
virt KVM: arm/arm64: Hold slots_lock when unregistering kvm io bus devices 2017-05-18 11:18:16 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS Email address update for Jessica Yu 2017-06-08 16:28:49 -07:00
Makefile Linux 4.12-rc4 2017-06-04 16:47:43 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.