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Larshin Sergey 2e7fd93b9c media: rc: fix races with imon_disconnect() 
commit fa0f61cc1d upstream.

Syzbot reports a KASAN issue as below:
BUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline]
BUG: KASAN: use-after-free in send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627
Read of size 4 at addr ffff8880256fb000 by task syz-executor314/4465

CPU: 2 PID: 4465 Comm: syz-executor314 Not tainted 6.0.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433
kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
__create_pipe include/linux/usb.h:1945 [inline]
send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627
vfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991
vfs_write+0x2d7/0xdd0 fs/read_write.c:576
ksys_write+0x127/0x250 fs/read_write.c:631
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The iMON driver improperly releases the usb_device reference in
imon_disconnect without coordinating with active users of the
device.

Specifically, the fields usbdev_intf0 and usbdev_intf1 are not
protected by the users counter (ictx->users). During probe,
imon_init_intf0 or imon_init_intf1 increments the usb_device
reference count depending on the interface. However, during
disconnect, usb_put_dev is called unconditionally, regardless of
actual usage.

As a result, if vfd_write or other operations are still in
progress after disconnect, this can lead to a use-after-free of
the usb_device pointer.

Thread 1 vfd_write                      Thread 2 imon_disconnect
                                        ...
                                        if
                                          usb_put_dev(ictx->usbdev_intf0)
                                        else
                                          usb_put_dev(ictx->usbdev_intf1)
...
while
  send_packet
    if
      pipe = usb_sndintpipe(
        ictx->usbdev_intf0) UAF
    else
      pipe = usb_sndctrlpipe(
        ictx->usbdev_intf0, 0) UAF

Guard access to usbdev_intf0 and usbdev_intf1 after disconnect by
checking ictx->disconnected in all writer paths. Add early return
with -ENODEV in send_packet(), vfd_write(), lcd_write() and
display_open() if the device is no longer present.

Set and read ictx->disconnected under ictx->lock to ensure memory
synchronization. Acquire the lock in imon_disconnect() before setting
the flag to synchronize with any ongoing operations.

Ensure writers exit early and safely after disconnect before the USB
core proceeds with cleanup.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Reported-by: syzbot+f1a69784f6efe748c3bf@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f1a69784f6efe748c3bf
Fixes: 21677cfc56 ("V4L/DVB: ir-core: add imon driver")
Cc: stable@vger.kernel.org

Signed-off-by: Larshin Sergey <Sergey.Larshin@kaspersky.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-10-06 11:20:05 +02:00
arch ARM fixes for 6.17 2025-09-28 13:24:43 -07:00
block blk-mq: fix blk_mq_tags double free while nr_requests grown 2025-10-06 11:20:04 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes a NULL pointer dereference in ccp and a couple of 2025-09-19 09:58:21 -07:00
Documentation i2c-for-6.17-rc8 2025-09-28 13:19:23 -07:00
drivers media: rc: fix races with imon_disconnect() 2025-10-06 11:20:05 +02:00
fs 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
include 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
init kbuild: Disable CC_HAS_ASM_GOTO_OUTPUT on clang < 17 2025-09-24 09:29:15 +02:00
io_uring io_uring-6.17-20250919 2025-09-19 12:10:49 -07:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel tracing fixes for v6.17 2025-09-28 10:26:35 -07:00
lib hardening fixes for v6.17-rc4 2025-08-31 08:56:45 -07:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
net nexthop: Forbid FDB status change while nexthop is in a group 2025-09-23 17:01:05 -07:00
rust Driver core fixes for 6.17-rc6 2025-09-13 10:36:06 -07:00
samples 15 hotfixes. 11 are cc:stable and the remainder address post-6.16 issues 2025-09-17 21:34:26 -07:00
scripts gcc-plugins: Remove TODO_verify_il for GCC >= 16 2025-10-06 11:20:04 +02:00
security + Features 2025-08-04 08:17:28 -07:00
sound ALSA: usb-audio: fix race condition to UAF in snd_usbmidi_free 2025-10-06 11:20:05 +02:00
tools Two fixes for rtla in v6.17: 2025-09-27 09:50:46 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge tag 'kvm-x86-no_assignment-6.17' of https://github.com/kvm-x86/linux into HEAD 2025-07-29 08:36:42 -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 scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore gitignore: allow .pylintrc to be tracked 2025-07-02 17:10:04 -06:00
.mailmap 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -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 MAINTAINERS: retire Boris from TLS maintainers 2025-08-26 17:36:01 -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 i2c-for-6.17-rc8 2025-09-28 13:19:23 -07:00
Makefile Linux 6.17 2025-09-28 14:39:22 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.