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Filename Latest commit message Latest commit date
Keiya Nobuta d5b0c0eafe usb: core: hub: Improved device recognition on remote wakeup
commit 9c06ac4c83df6d6fbdbf7488fbad822b4002ba19 upstream.

If hub_activate() is called before D+ has stabilized after remote
wakeup, the following situation might occur:

         __      ___________________
        /  \    /
D+   __/    \__/

Hub  _______________________________
          |  ^   ^           ^
          |  |   |           |
Host _____v__|___|___________|______
          |  |   |           |
          |  |   |           \-- Interrupt Transfer (*3)
          |  |    \-- ClearPortFeature (*2)
          |   \-- GetPortStatus (*1)
          \-- Host detects remote wakeup

- D+ goes high, Host starts running by remote wakeup
- D+ is not stable, goes low
- Host requests GetPortStatus at (*1) and gets the following hub status:
  - Current Connect Status bit is 0
  - Connect Status Change bit is 1
- D+ stabilizes, goes high
- Host requests ClearPortFeature and thus Connect Status Change bit is
  cleared at (*2)
- After waiting 100 ms, Host starts the Interrupt Transfer at (*3)
- Since the Connect Status Change bit is 0, Hub returns NAK.

In this case, port_event() is not called in hub_event() and Host cannot
recognize device. To solve this issue, flag change_bits even if only
Connect Status Change bit is 1 when got in the first GetPortStatus.

This issue occurs rarely because it only if D+ changes during a very
short time between GetPortStatus and ClearPortFeature. However, it is
fatal if it occurs in embedded system.

Signed-off-by: Keiya Nobuta <nobuta.keiya@fujitsu.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20200109051448.28150-1-nobuta.keiya@fujitsu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-23 08:22:36 +01:00
arch ARM: davinci: select CONFIG_RESET_CONTROLLER 2020-01-23 08:22:32 +01:00
block block: fix an integer overflow in logical block size 2020-01-23 08:22:32 +01:00
certs
crypto crypto: algif_skcipher - Use chunksize instead of blocksize 2020-01-17 19:48:46 +01:00
Documentation mei: fix modalias documentation 2020-01-17 19:48:48 +01:00
drivers usb: core: hub: Improved device recognition on remote wakeup 2020-01-23 08:22:36 +01:00
fs io_uring: only allow submit from owning task 2020-01-23 08:22:32 +01:00
include block: fix an integer overflow in logical block size 2020-01-23 08:22:32 +01:00
init
ipc
kernel ptrace: reintroduce usage of subjective credentials in ptrace_has_cap() 2020-01-23 08:22:36 +01:00
lib
LICENSES
mm uaccess: Add non-pagefault user-space write function 2020-01-17 19:48:40 +01:00
net rxrpc: Fix missing security check on incoming calls 2020-01-17 19:49:05 +01:00
samples
scripts kbuild/deb-pkg: annotate libelf-dev dependency as :native 2020-01-17 19:49:07 +01:00
security tomoyo: Suppress RCU warning at list_for_each_entry_rcu(). 2020-01-17 19:49:05 +01:00
sound ALSA: usb-audio: fix sync-ep altsetting sanity check 2020-01-23 08:22:31 +01:00
tools rseq/selftests: Turn off timeout setting 2020-01-17 19:49:04 +01:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.13 2020-01-17 19:49:08 +01:00
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.