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Benjamin Tissoires 0d0777ccaa HID: core: ensure __hid_request reserves the report ID as the first byte
The low level transport driver expects the first byte to be the report
ID, even when the report ID is not use (in which case they just shift
the buffer).

However, __hid_request() whas not offsetting the buffer it used by one
in this case, meaning that the raw_request() callback emitted by the
transport driver would be stripped of the first byte.

Note: this changes the API for uhid devices when a request is made
through hid_hw_request. However, several considerations makes me think
this is fine:
- every request to a HID device made through hid_hw_request() would see
  that change, but every request made through hid_hw_raw_request()
  already has the new behaviour. So that means that the users are
  already facing situations where they might have or not the first byte
  being the null report ID when it is 0. We are making things more
  straightforward in the end.
- uhid is mainly used for BLE devices
- uhid is also used for testing, but I don't see that change a big issue
- for BLE devices, we can check which kernel module is calling
  hid_hw_request()
- and in those modules, we can check which are using a Bluetooth device
- and then we can check if the command is used with a report ID or not.
- surprise: none of the kernel module are using a report ID 0
- and finally, bluez, in its function set_report()[0], does the same
  shift if the report ID is 0 and the given buffer has a size > 0.

[0] https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/profiles/input/hog-lib.c#n879

Reported-by: Alan Stern <stern@rowland.harvard.edu>
Closes: https://lore.kernel.org/linux-input/c75433e0-9b47-4072-bbe8-b1d14ea97b13@rowland.harvard.edu/
Reported-by: syzbot+8258d5439c49d4c35f43@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8258d5439c49d4c35f43
Tested-by: syzbot+8258d5439c49d4c35f43@syzkaller.appspotmail.com
Fixes: 4fa5a7f76c ("HID: core: implement generic .request()")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250710-report-size-null-v2-2-ccf922b7c4e5@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
2025-07-13 09:53:27 +02:00
arch Xtensa updates for v6.16 2025-06-03 09:05:01 -07:00
block cgroup: Changes for v6.16 2025-05-27 20:59:53 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto EFI updates for v6.16 2025-05-30 12:42:57 -07:00
Documentation ata changes for 6.16-rc1 2025-06-03 09:42:38 -07:00
drivers HID: core: ensure __hid_request reserves the report ID as the first byte 2025-07-13 09:53:27 +02:00
fs - The 2 patch series "zram: support algorithm-specific parameters" from 2025-06-02 16:00:26 -07:00
include hid-for-linus-2025060301 2025-06-03 10:34:36 -07:00
init - The 2 patch series "zram: support algorithm-specific parameters" from 2025-06-02 16:00:26 -07:00
io_uring Networking changes for 6.16. 2025-05-28 15:24:36 -07:00
ipc - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
kernel Modules changes for 6.16-rc1 2025-06-02 17:35:06 -07:00
lib bitmap-for-6.16 2025-06-03 07:39:23 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm - The 2 patch series "zram: support algorithm-specific parameters" from 2025-06-02 16:00:26 -07:00
net vfs-6.16-rc1.netfs 2025-06-02 15:04:06 -07:00
rust - The 2 patch series "zram: support algorithm-specific parameters" from 2025-06-02 16:00:26 -07:00
samples - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
scripts - The 2 patch series "zram: support algorithm-specific parameters" from 2025-06-02 16:00:26 -07:00
security require gcc-8 and binutils-2.30 2025-05-31 08:16:52 -07:00
sound sound updates for 6.16-rc1 2025-05-27 15:05:18 -07:00
tools hyperv-next for v6.16 2025-06-03 08:39:20 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge branch 'kvm-lockdep-common' into HEAD 2025-05-28 06:29:17 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore Python compiled bytecode 2025-04-24 10:12:46 -06:00
.mailmap - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Update Christoph's Email address and make it consistent 2025-05-12 23:50:31 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS hwmon updates for v6.16 2025-06-03 09:11:26 -07:00
Makefile A moderately busy cycle for documentation this time around: 2025-05-27 11:22:19 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.