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Linux kernel for uConsole
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Halil Pasic 2a622040a8 virtio/s390: fix race in ccw_io_helper() 
commit 78b1a52e05 upstream.

While ccw_io_helper() seems like intended to be exclusive in a sense that
it is supposed to facilitate I/O for at most one thread at any given
time, there is actually nothing ensuring that threads won't pile up at
vcdev->wait_q. If they do, all threads get woken up and see the status
that belongs to some other request than their own. This can lead to bugs.
For an example see:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1788432

This race normally does not cause any problems. The operations provided
by struct virtio_config_ops are usually invoked in a well defined
sequence, normally don't fail, and are normally used quite infrequent
too.

Yet, if some of the these operations are directly triggered via sysfs
attributes, like in the case described by the referenced bug, userspace
is given an opportunity to force races by increasing the frequency of the
given operations.

Let us fix the problem by ensuring, that for each device, we finish
processing the previous request before starting with a new one.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Reported-by: Colin Ian King <colin.king@canonical.com>
Cc: stable@vger.kernel.org
Message-Id: <20180925121309.58524-3-pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-13 09:16:18 +01:00
arch parisc: Enable -ffunction-sections for modules on 32-bit kernel 2018-12-13 09:16:18 +01:00
block blk-mq: punt failed direct issue to dispatch list 2018-12-08 12:59:10 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: simd - correctly take reqsize of wrapped skcipher into account 2018-12-01 09:37:32 +01:00
Documentation x86/speculation: Provide IBPB always command line options 2018-12-05 19:32:04 +01:00
drivers virtio/s390: fix race in ccw_io_helper() 2018-12-13 09:16:18 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs flexfiles: use per-mirror specified stateid for IO 2018-12-13 09:16:14 +01:00
include ALSA: pcm: Fix interval evaluation with openmin/max 2018-12-13 09:16:16 +01:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel tracing/fgraph: Fix set_graph_function from showing interrupts 2018-12-08 12:59:07 +01:00
lib test_firmware: fix error return getting clobbered 2018-12-13 09:16:10 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not set 2018-12-08 12:59:08 +01:00
net batman-adv: Expand merged fragment buffer for full packet 2018-12-13 09:16:10 +01:00
samples samples: disable CONFIG_SAMPLES for UML 2018-10-11 02:15:46 +09:00
scripts unifdef: use memcpy instead of strncpy 2018-12-08 12:59:06 +01:00
security selinux: add support for RTM_NEWCHAIN, RTM_DELCHAIN, and RTM_GETCHAIN 2018-12-08 12:59:08 +01:00
sound ALSA: hda/realtek: Fix mic issue on Acer AIO Veriton Z4860G/Z6860G 2018-12-13 09:16:17 +01:00
tools tc-testing: tdc.py: Guard against lack of returncode in executed command 2018-12-13 09:16:13 +01:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm64: Fix caching of host MDCR_EL2 value 2018-11-13 11:08:47 -08:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.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 libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
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: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile Linux 4.19.8 2018-12-08 12:59:10 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.