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Maxime Jayat 156b45ed22 dmaengine: at_xdmac: fix rare residue corruption
commit c5637476bb upstream.

Despite the efforts made to correctly read the NDA and CUBC registers,
the order in which the registers are read could sometimes lead to an
inconsistent state.

Re-using the timeline from the comments, this following timing of
registers reads could lead to reading NDA with value "@desc2" and
CUBC with value "MAX desc1":

 INITD --------                    ------------
              |____________________|
       _______________________  _______________
 NDA       @desc2             \/   @desc3
       _______________________/\_______________
       __________  ___________  _______________
 CUBC       0    \/ MAX desc1 \/  MAX desc2
       __________/\___________/\_______________
        |  |          |  |
Events:(1)(2)        (3)(4)

(1) check_nda = @desc2
(2) initd = 1
(3) cur_ubc = MAX desc1
(4) cur_nda = @desc2

This is allowed by the condition ((check_nda == cur_nda) && initd),
despite cur_ubc and cur_nda being in the precise state we don't want.

This error leads to incorrect residue computation.

Fix it by inversing the order in which CUBC and INITD are read. This
makes sure that NDA and CUBC are always read together either _before_
INITD goes to 0 or _after_ it is back at 1.
The case where NDA is read before INITD is at 0 and CUBC is read after
INITD is back at 1 will be rejected by check_nda and cur_nda being
different.

Fixes: 53398f4888 ("dmaengine: at_xdmac: fix residue corruption")
Cc: stable@vger.kernel.org
Signed-off-by: Maxime Jayat <maxime.jayat@mobile-devices.fr>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24 09:36:32 +02:00
Documentation serial: 8250: Add Nuvoton NPCM UART 2018-04-08 14:26:30 +02:00
arch powerpc/powernv: Fix OPAL NVRAM driver OPAL_BUSY loops 2018-04-24 09:36:28 +02:00
block blk-mq: don't keep offline CPUs mapped to hctx 0 2018-04-19 08:56:20 +02:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: aes-generic - build with -Os on gcc-7+ 2018-04-12 12:32:20 +02:00
drivers dmaengine: at_xdmac: fix rare residue corruption 2018-04-24 09:36:32 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs ext4: add extra checks to ext4_xattr_block_get() 2018-04-24 09:36:31 +02:00
include block: use 32-bit blk_status_t on Alpha 2018-04-24 09:36:29 +02:00
init kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2018-02-22 15:42:23 +01:00
ipc ipc/shm: fix use-after-free of shm file via remap_file_pages() 2018-04-24 09:36:23 +02:00
kernel resource: fix integer overflow at reallocation 2018-04-24 09:36:22 +02:00
lib lib: fix stall in __bitmap_parselist() 2018-04-19 08:56:20 +02:00
mm mm, slab: reschedule cache_reap() on the same CPU 2018-04-24 09:36:23 +02:00
net sunrpc: remove incorrect HMAC request initialization 2018-04-19 08:56:20 +02:00
samples samples/bpf: adjust rlimit RLIMIT_MEMLOCK for xdp1 2017-12-20 10:10:31 +01:00
scripts kbuild: fix linker feature test macros when cross compiling with Clang 2018-03-24 11:01:29 +01:00
security apparmor: fix resource audit messages when auditing peer 2018-04-19 08:56:18 +02:00
sound ALSA: pcm: Fix UAF at PCM release via PCM timer access 2018-04-24 09:36:31 +02:00
tools perf intel-pt: Fix timestamp following overflow 2018-04-19 08:56:17 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: vgic-its: Fix potential overrun in vgic_copy_lpi_list 2018-04-24 09:36:23 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.35 2018-04-19 08:56:21 +02:00
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.