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Duoming Zhou c3363db5d0 net: mscc: ocelot: Fix use-after-free caused by cyclic delayed work 
[ Upstream commit bc9ea78707 ]

The origin code calls cancel_delayed_work() in ocelot_stats_deinit()
to cancel the cyclic delayed work item ocelot->stats_work. However,
cancel_delayed_work() may fail to cancel the work item if it is already
executing. While destroy_workqueue() does wait for all pending work items
in the work queue to complete before destroying the work queue, it cannot
prevent the delayed work item from being rescheduled within the
ocelot_check_stats_work() function. This limitation exists because the
delayed work item is only enqueued into the work queue after its timer
expires. Before the timer expiration, destroy_workqueue() has no visibility
of this pending work item. Once the work queue appears empty,
destroy_workqueue() proceeds with destruction. When the timer eventually
expires, the delayed work item gets queued again, leading to the following
warning:

workqueue: cannot queue ocelot_check_stats_work on wq ocelot-switch-stats
WARNING: CPU: 2 PID: 0 at kernel/workqueue.c:2255 __queue_work+0x875/0xaf0
...
RIP: 0010:__queue_work+0x875/0xaf0
...
RSP: 0018:ffff88806d108b10 EFLAGS: 00010086
RAX: 0000000000000000 RBX: 0000000000000101 RCX: 0000000000000027
RDX: 0000000000000027 RSI: 0000000000000004 RDI: ffff88806d123e88
RBP: ffffffff813c3170 R08: 0000000000000000 R09: ffffed100da247d2
R10: ffffed100da247d1 R11: ffff88806d123e8b R12: ffff88800c00f000
R13: ffff88800d7285c0 R14: ffff88806d0a5580 R15: ffff88800d7285a0
FS:  0000000000000000(0000) GS:ffff8880e5725000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe18e45ea10 CR3: 0000000005e6c000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 ? kasan_report+0xc6/0xf0
 ? __pfx_delayed_work_timer_fn+0x10/0x10
 ? __pfx_delayed_work_timer_fn+0x10/0x10
 call_timer_fn+0x25/0x1c0
 __run_timer_base.part.0+0x3be/0x8c0
 ? __pfx_delayed_work_timer_fn+0x10/0x10
 ? rcu_sched_clock_irq+0xb06/0x27d0
 ? __pfx___run_timer_base.part.0+0x10/0x10
 ? try_to_wake_up+0xb15/0x1960
 ? _raw_spin_lock_irq+0x80/0xe0
 ? __pfx__raw_spin_lock_irq+0x10/0x10
 tmigr_handle_remote_up+0x603/0x7e0
 ? __pfx_tmigr_handle_remote_up+0x10/0x10
 ? sched_balance_trigger+0x1c0/0x9f0
 ? sched_tick+0x221/0x5a0
 ? _raw_spin_lock_irq+0x80/0xe0
 ? __pfx__raw_spin_lock_irq+0x10/0x10
 ? tick_nohz_handler+0x339/0x440
 ? __pfx_tmigr_handle_remote_up+0x10/0x10
 __walk_groups.isra.0+0x42/0x150
 tmigr_handle_remote+0x1f4/0x2e0
 ? __pfx_tmigr_handle_remote+0x10/0x10
 ? ktime_get+0x60/0x140
 ? lapic_next_event+0x11/0x20
 ? clockevents_program_event+0x1d4/0x2a0
 ? hrtimer_interrupt+0x322/0x780
 handle_softirqs+0x16a/0x550
 irq_exit_rcu+0xaf/0xe0
 sysvec_apic_timer_interrupt+0x70/0x80
 </IRQ>
...

The following diagram reveals the cause of the above warning:

CPU 0 (remove)             | CPU 1 (delayed work callback)
mscc_ocelot_remove()       |
  ocelot_deinit()          | ocelot_check_stats_work()
    ocelot_stats_deinit()  |
      cancel_delayed_work()|   ...
                           |   queue_delayed_work()
      destroy_workqueue()  | (wait a time)
                           | __queue_work() //UAF

The above scenario actually constitutes a UAF vulnerability.

The ocelot_stats_deinit() is only invoked when initialization
failure or resource destruction, so we must ensure that any
delayed work items cannot be rescheduled.

Replace cancel_delayed_work() with disable_delayed_work_sync()
to guarantee proper cancellation of the delayed work item and
ensure completion of any currently executing work before the
workqueue is deallocated.

A deadlock concern was considered: ocelot_stats_deinit() is called
in a process context and is not holding any locks that the delayed
work item might also need. Therefore, the use of the _sync() variant
is safe here.

This bug was identified through static analysis. To reproduce the
issue and validate the fix, I simulated ocelot-switch device by
writing a kernel module and prepared the necessary resources for
the virtual ocelot-switch device's probe process. Then, removing
the virtual device will trigger the mscc_ocelot_remove() function,
which in turn destroys the workqueue.

Fixes: a556c76adc ("net: mscc: Add initial Ocelot switch support")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://patch.msgid.link/20251001011149.55073-1-duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-10-19 16:37:10 +02:00
arch LoongArch: Init acpi_gbl_use_global_lock to false 2025-10-19 16:37:08 +02:00
block blk-throttle: fix throtl_data leak during disk release 2025-10-15 12:03:34 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto KEYS: X.509: Fix Basic Constraints CA flag parsing 2025-10-15 12:04:11 +02:00
Documentation Documentation: trace: historgram-design: Separate sched_waking histogram section heading and the following diagram 2025-10-15 12:04:01 +02:00
drivers net: mscc: ocelot: Fix use-after-free caused by cyclic delayed work 2025-10-19 16:37:10 +02:00
fs nfsd: fix timestamp updates in CB_GETATTR 2025-10-19 16:37:06 +02:00
include vfs: add ATTR_CTIME_SET flag 2025-10-19 16:37:06 +02:00
init Fix CC_HAS_ASM_GOTO_OUTPUT on non-x86 architectures 2025-10-15 12:03:13 +02:00
io_uring io_uring/zcrx: fix overshooting recv limit 2025-10-15 12:04:15 +02:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel rseq: Protect event mask against membarrier IPI 2025-10-19 16:36:59 +02:00
lib vdso/datastore: Gate time data behind CONFIG_GENERIC_GETTIMEOFDAY 2025-10-15 12:03:24 +02:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm memcg: skip cgroup_file_notify if spinning is not allowed 2025-10-19 16:37:00 +02:00
net tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request(). 2025-10-19 16:37:10 +02:00
rust cpufreq: Make drivers using CPUFREQ_ETERNAL specify transition latency 2025-10-19 16:37:00 +02:00
samples 15 hotfixes. 11 are cc:stable and the remainder address post-6.16 issues 2025-09-17 21:34:26 -07:00
scripts scripts/misc-check: update export checks for EXPORT_SYMBOL_FOR_MODULES() 2025-10-15 12:03:22 +02:00
security lsm: CONFIG_LSM can depend on CONFIG_SECURITY 2025-10-15 12:03:17 +02:00
sound ASoC: SOF: Intel: Read the LLP via the associated Link DMA channel 2025-10-19 16:37:09 +02:00
tools perf bpf_counter: Fix handling of cpumap fixing hybrid 2025-10-19 16:37:08 +02:00
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 6.17.3 2025-10-15 12:04:23 +02:00
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.