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Johan Hovold c32dfec6c1 USB: serial: cp210x: fix dropped characters with CP2102
Some CP2102 do not support event-insertion mode but return no error when
attempting to enable it.

This means that any event escape characters in the input stream will not
be escaped by the device and consequently regular data may be
interpreted as escape sequences and be removed from the stream by the
driver.

The reporter's device has batch number DCL00X etched into it and as
discovered by the SHA2017 Badge team, counterfeit devices with that
marking can be detected by sending malformed vendor requests. [1][2]

Tests confirm that the possibly counterfeit CP2102 returns a single byte
in response to a malformed two-byte part-number request, while an
original CP2102 returns two bytes. Assume that every CP2102 that behaves
this way also does not support event-insertion mode (e.g. cannot report
parity errors).

[1] https://mobile.twitter.com/sha2017badge/status/1167902087289532418
[2] https://hackaday.com/2017/08/14/hands-on-with-the-shacamp-2017-badge/#comment-3903376

Reported-by: Malte Di Donato <malte@neo-soft.org>
Tested-by: Malte Di Donato <malte@neo-soft.org>
Fixes: a7207e9835 ("USB: serial: cp210x: add support for line-status events")
Cc: stable@vger.kernel.org	# 5.9
Link: https://lore.kernel.org/r/20210922113100.20888-1-johan@kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
2021-09-23 10:44:46 +02:00
arch Updates for the SMP and CPU hotplug: 2021-09-12 12:42:51 -07:00
block block-5.15-2021-09-11 2021-09-11 10:19:51 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation An assortment of improvements for auxdisplay: 2021-09-12 16:00:49 -07:00
drivers USB: serial: cp210x: fix dropped characters with CP2102 2021-09-23 10:44:46 +02:00
fs Merge branch 'misc.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-09-12 10:43:51 -07:00
include Compiler Attributes improvements: 2021-09-12 16:09:26 -07:00
init More tracing updates for 5.15: 2021-09-09 13:11:15 -07:00
ipc ARM development updates for 5.15: 2021-09-09 13:25:49 -07:00
kernel - Make sure the idle timer expires in hardirq context, on PREEMPT_RT 2021-09-12 11:37:41 -07:00
lib Minor fixes to the processing of the bootconfig tree. 2021-09-11 10:16:30 -07:00
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mm ARM development updates for 5.15: 2021-09-09 13:25:49 -07:00
net virtio,vdpa,vhost: features, fixes 2021-09-11 14:48:42 -07:00
samples kgdb patches for 5.15 2021-09-07 12:08:04 -07:00
scripts RISC-V Patches for the 5.15 Merge Window, Part 2 2021-09-11 14:29:42 -07:00
security Kbuild updates for v5.15 2021-09-03 15:33:47 -07:00
sound sound fixes for 5.15-rc1 2021-09-09 16:05:10 -07:00
tools perf tools changes for v5.15: 2nd batch 2021-09-12 16:18:15 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Drop unused kvm_dirty_gfn_invalid() 2021-09-06 08:23:46 -04:00
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Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Compiler Attributes improvements: 2021-09-12 16:09:26 -07:00
Makefile Linux 5.15-rc1 2021-09-12 16:28:37 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.