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Ard Biesheuvel e2cee489f2 efi: tpm: Avoid READ_ONCE() for accessing the event log
commit d3f450533b upstream.

Nathan reports that recent kernels built with LTO will crash when doing
EFI boot using Fedora's GRUB and SHIM. The culprit turns out to be a
misaligned load from the TPM event log, which is annotated with
READ_ONCE(), and under LTO, this gets translated into a LDAR instruction
which does not tolerate misaligned accesses.

Interestingly, this does not happen when booting the same kernel
straight from the UEFI shell, and so the fact that the event log may
appear misaligned in memory may be caused by a bug in GRUB or SHIM.

However, using READ_ONCE() to access firmware tables is slightly unusual
in any case, and here, we only need to ensure that 'event' is not
dereferenced again after it gets unmapped, but this is already taken
care of by the implicit barrier() semantics of the early_memunmap()
call.

Cc: <stable@vger.kernel.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/1782
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-18 11:58:10 +01:00
Documentation KVM: x86: Do not return host topology information from KVM_GET_SUPPORTED_CPUID 2023-01-18 11:58:10 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch KVM: arm64: Fix S1PTW handling on RO memslots 2023-01-18 11:58:10 +01:00
block block: don't allow splitting of a REQ_NOWAIT bio 2023-01-12 12:02:47 +01:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto crypto: tcrypt - Fix multibuffer skcipher speed test mem leak 2022-12-31 13:32:34 +01:00
drivers efi: fix userspace infinite retry read efivars after EFI runtime services page fault 2023-01-18 11:58:10 +01:00
fs Revert "SUNRPC: Use RMW bitops in single-threaded hot paths" 2023-01-14 10:33:42 +01:00
include efi: tpm: Avoid READ_ONCE() for accessing the event log 2023-01-18 11:58:10 +01:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-14 10:33:43 +01:00
io_uring io_uring: fix CQ waiting timeout handling 2023-01-12 12:02:48 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Fix panic due to wrong pageattr of im->image 2023-01-12 12:02:45 +01:00
lib kunit: alloc_string_stream_fragment error handling bug fix 2023-01-12 12:02:41 +01:00
mm hugetlb: really allocate vma lock for all sharable vmas 2023-01-07 11:11:55 +01:00
net netfilter: nft_payload: incorrect arithmetics when fetching VLAN header bits 2023-01-18 11:58:09 +01:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2022-12-31 13:32:42 +01:00
scripts - Handle different output of readelf on different distros running 2022-11-27 12:08:17 -08:00
security device_cgroup: Roll back to original exceptions after copy failure 2023-01-07 11:11:56 +01:00
sound ALSA: hda/realtek: Enable mute/micmute LEDs on HP Spectre x360 13-aw0xxx 2023-01-18 11:58:09 +01:00
tools selftests/vm/pkeys: Add a regression test for setting PKRU through ptrace 2023-01-14 10:33:42 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-dwmw2-fixes' into HEAD 2022-11-23 18:59:45 -05:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
Makefile Linux 6.1.6 2023-01-14 10:33:46 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.