From nobody Wed Oct 1 21:24:14 2025 Received: from zg8tmja2lje4os43os4xodqa.icoremail.net (zg8tmja2lje4os43os4xodqa.icoremail.net [206.189.79.184]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C5F32199E89; Wed, 1 Oct 2025 01:12:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=206.189.79.184 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759281158; cv=none; b=dQ4qZqh/mHCTgCi4twzpmNpZOArjEDfQELYguvfvpVz9J0FH0Q8cijMQQbhhkXMuyzKcHFIcSz+m+jwAu26/Q2nJHkY5TOGVqevCWe3tm3eH87Y0mXDbziknxQfOTTl+LzHBsDzNzJiKDiK31SEHehqvgY5K2pHlnDMqHiCjAio= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759281158; c=relaxed/simple; bh=q0JdKKTXzAih7r1RyDvfJtbjpNr/H6/DDu4JY/5CF1M=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=VEtvf/s4CU1c6vJcsNBTMNJKuhMs7X2WjFMWu3mEuw27rpogpGTS2Fdk73K/YUmVt/IlPKtCb+RMqrDD93BbNSjLijORra+aZ99ikoZ3e+El4jRLcU0zYXuRgmomVPa7L1ZkfFubsX4O0XsCd71f5vrQGc40224GPJga9f61+aw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=206.189.79.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from zju.edu.cn (unknown [218.12.19.54]) by mtasvr (Coremail) with SMTP id _____wBXImref9xo9vmOAg--.18271S3; Wed, 01 Oct 2025 09:11:59 +0800 (CST) Received: from ubuntu.localdomain (unknown [218.12.19.54]) by mail-app2 (Coremail) with SMTP id zC_KCgBHX0PYf9xol2tyAg--.36817S2; Wed, 01 Oct 2025 09:11:57 +0800 (CST) From: Duoming Zhou To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, pabeni@redhat.com, kuba@kernel.org, edumazet@google.com, davem@davemloft.net, andrew+netdev@lunn.ch, UNGLinuxDriver@microchip.com, alexandre.belloni@bootlin.com, claudiu.manoil@nxp.com, vladimir.oltean@nxp.com, Duoming Zhou Subject: [PATCH v2 net] net: mscc: ocelot: Fix use-after-free caused by cyclic delayed work Date: Wed, 1 Oct 2025 09:11:49 +0800 Message-Id: <20251001011149.55073-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zC_KCgBHX0PYf9xol2tyAg--.36817S2 X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAwcFAWja4PwNmwBXsv X-CM-DELIVERINFO: =?B?ZyILFQXKKxbFmtjJiESix3B1w3uoVhYI+vyen2ZzBEkOnu5chDpkB+ZdGnv/zQ0PbP CR18SN7MKHUZcowJmI/0r0+FuZkoxDnL9qxjx8CbkOtwEWXF1pVDRDKTRMEzIdZgkDnI84 L7LJngXVdj3aU/9+ZkIg0M1swJt1lqBa7L+lo6kJcaim2N7Nn+Z2cKbEYgHFLw== X-Coremail-Antispam: 1Uk129KBj93XoWxKr1xuw18uFy3Ar1rCw45urX_yoW7XF4Up3 y5K3y7C3y8Xw4jqFs0vr40qw15KFnYkFsrJr4xZr4UC3WrJr15XF18tFWY9FWDJrWkZFyS va1DX392ya4qyabCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUB0b4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26F4UJVW0owA2z4x0Y4vEx4A2jsIEc7CjxVAF wI0_Cr1j6rxdM2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2x26I8E6xACxx 1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv 67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7xvr2IYc2 Ij64vIr40E4x8a64kEw24lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IYc2Ij64vIr41l 4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67 AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8I cVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI 8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v2 6r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxU7xwIDUUUU Content-Type: text/plain; charset="utf-8" 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: ? 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 ... 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: a556c76adc05 ("net: mscc: Add initial Ocelot switch support") Signed-off-by: Duoming Zhou --- Changes in v2: - Replace cancel_delayed_work() with disable_delayed_work_sync(). drivers/net/ethernet/mscc/ocelot_stats.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/mscc/ocelot_stats.c b/drivers/net/etherne= t/mscc/ocelot_stats.c index 545710dadcf5..d2be1be37716 100644 --- a/drivers/net/ethernet/mscc/ocelot_stats.c +++ b/drivers/net/ethernet/mscc/ocelot_stats.c @@ -1021,6 +1021,6 @@ int ocelot_stats_init(struct ocelot *ocelot) =20 void ocelot_stats_deinit(struct ocelot *ocelot) { - cancel_delayed_work(&ocelot->stats_work); + disable_delayed_work_sync(&ocelot->stats_work); destroy_workqueue(ocelot->stats_queue); } --=20 2.34.1