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Hans de Goede ae6b3e54aa ACPICA: Fix handling of buffer-size in acpi_ex_write_data_to_field()
Generic Serial Bus transfers use a data struct like this:

struct gsb_buffer {
        u8      status;
        u8      len;
        u8      data[0];
};

acpi_ex_write_data_to_field() copies the data which is to be written from
the source-buffer to a temp-buffer. This is done because the OpReg-handler
overwrites the status field and some transfers do a write + read-back.

Commit f99b89eefe ("ACPICA: Update for generic_serial_bus and
attrib_raw_process_bytes protocol") acpi_ex_write_data_to_field()
introduces a number of problems with this:

 1) It drops a "length += 2" statement used to calculate the temp-buffer
 size causing the temp-buffer to only be 1/2 bytes large for byte/word
 transfers while it should be 3/4 bytes (taking the status and len field
 into account). This is already fixed in commit e324e10109 ("ACPICA:
 Update for field unit access") which refactors the code.

The ACPI 6.0 spec (ACPI_6.0.pdf) "5.5.2.4.5.2 Declaring and Using a
GenericSerialBusData Buffer" (page 232) states that the GenericSerialBus
Data Buffer Length field is only valid when doing a Read/Write Block
(AttribBlock) transfer, but since the troublesome commit we unconditionally
use the len field to determine how much data to copy from the source-buffer
into the temp-buffer passed to the OpRegion.

This causes 3 further issues:

 2) This may lead to not copying enough data to the temp-buffer causing the
 OpRegion handler for the serial-bus to write garbage to the hardware.

 3) The temp-buffer passed to the OpRegion is allocated to the size
 returned by acpi_ex_get_serial_access_length(), which may be as little
 as 1, so potentially this may lead to a write overflow of the temp-buffer.

 4) Commit e324e10109 ("ACPICA: Update for field unit access") drops a
 length check on the source-buffer, leading to a potential read overflow
 of the source-buffer.

This commit fixes all 3 remaining issues by not looking at the len field at
all (the interpretation of this field is left up to the OpRegion handler),
and copying the minimum of the source- and temp-buffer sizes from the
source-buffer to the temp-buffer.

This fixes e.g. an Acer S1003 no longer booting since the troublesome
commit.

Fixes: f99b89eefe (ACPICA: Update for generic_serial_bus and ...)
Fixes: e324e10109 (ACPICA: Update for field unit access)
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-11-19 11:06:09 +01:00
Documentation Power management updates for 4.20-rc3 2018-11-14 15:33:45 -06:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-18 10:54:59 -08:00
block SCSI: fix queue cleanup race before queue initialization is done 2018-11-14 08:19:10 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: user - Zeroize whole structure given to user space 2018-11-09 17:35:43 +08:00
drivers ACPICA: Fix handling of buffer-size in acpi_ex_write_data_to_field() 2018-11-19 11:06:09 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs ocfs2: free up write context when direct IO failed 2018-11-18 10:15:09 -08:00
include Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-18 10:52:26 -08:00
init memblock: stop using implicit alignment to SMP_CACHE_BYTES 2018-10-31 08:54:16 -07:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge branch 'akpm' (patches from Andrew) 2018-11-18 11:31:26 -08:00
lib lib/ubsan.c: don't mark __ubsan_handle_builtin_unreachable as noreturn 2018-11-18 10:15:10 -08:00
mm mm/memblock.c: fix a typo in __next_mem_pfn_range() comments 2018-11-18 10:15:10 -08:00
net NFS client bugfixes for Linux 4.20 2018-11-15 10:59:37 -06:00
samples VFIO updates for v4.20 2018-10-31 11:01:38 -07:00
scripts scripts/spdxcheck.py: make python3 compliant 2018-11-18 10:15:10 -08:00
security selinux/stable-4.20 PR 20181115 2018-11-15 11:26:09 -06:00
sound ALSA: hda - Fix incorrect clearance of thinkpad_acpi hooks 2018-11-06 16:33:53 +01:00
tools libnvdimm 4.20-rc3 2018-11-18 12:21:09 -08:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks" 2018-10-26 16:25:19 -07:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.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 updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap mailmap: Update email for Punit Agrawal 2018-11-05 10:02:11 +00:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: update OMAP MMC entry 2018-11-18 10:15:09 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: update OMAP MMC entry 2018-11-18 10:15:09 -08:00
Makefile Linux 4.20-rc3 2018-11-18 13:33:44 -08:00
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.