From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9E2D819D074 for ; Wed, 22 Oct 2025 11:02:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761130969; cv=none; b=KtpzEtVDR+K3fneE/u9SAd25TaPotIaF+S6u6rB8ofSJ2TX+RJY+X6Rk/wl4koVccsycrZj0eBb3tnd8irECdx8I3Mw6Y570s1BrzV0O2R8WSOmTvDA3tSGGWmvR+Jz4ohRgEg20qk85C7DfSitqw0sqYly4llLOQD2aRr4RXJk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761130969; c=relaxed/simple; bh=ZyEF/RL1pft+ckVefYF1LGuyMxaoM8RNwGAC+KmPfSc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kNyXFF8kOu6WiB6D57jn2CCe3u7XaWLKv3kW3ocy8bc+IuPd4tMciQbQNbEdYy908kRRUMTZES5dGaiqlR+BTtkiMTjgBkTGfS+xx6myyR9u+XiQ4t/tPvAyVsUHaMEZz0IwHXZaUsyZ88YbASutJcZVKkYOU42bDB9RNV0v1aE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 24B7C1C00 for ; Wed, 22 Oct 2025 04:02:39 -0700 (PDT) Received: from e110455-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id BE5D83F59E for ; Wed, 22 Oct 2025 04:02:46 -0700 (PDT) Date: Wed, 22 Oct 2025 12:02:34 +0100 From: Liviu Dudau To: Ketil Johnsen Cc: Boris Brezillon , Steven Price , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Heiko Stuebner , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] drm/panthor: Fix UAF race between device unplug and FW event processing Message-ID: References: <20251022103014.1082629-1-ketil.johnsen@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20251022103014.1082629-1-ketil.johnsen@arm.com> On Wed, Oct 22, 2025 at 12:30:13PM +0200, Ketil Johnsen wrote: > The function panthor_fw_unplug() will free the FW memory sections. > The problem is that there could still be pending FW events which are yet > not handled at this point. process_fw_events_work() can in this case try > to access said freed memory. > > This fix introduces a destroyed state for the panthor_scheduler object, > and we check for this before processing FW events. > > Signed-off-by: Ketil Johnsen > Fixes: de85488138247 ("drm/panthor: Add the scheduler logical block") Reviewed-by: Liviu Dudau Best regards, Liviu > --- > v2: > - Followed Boris's advice and handle the race purely within the > scheduler block (by adding a destroyed state) > --- > drivers/gpu/drm/panthor/panthor_sched.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c > index 0cc9055f4ee52..4996f987b8183 100644 > --- a/drivers/gpu/drm/panthor/panthor_sched.c > +++ b/drivers/gpu/drm/panthor/panthor_sched.c > @@ -315,6 +315,13 @@ struct panthor_scheduler { > */ > struct list_head stopped_groups; > } reset; > + > + /** > + * @destroyed: Scheduler object is (being) destroyed > + * > + * Normal scheduler operations should no longer take place. > + */ > + bool destroyed; > }; > > /** > @@ -1765,7 +1772,10 @@ static void process_fw_events_work(struct work_struct *work) > u32 events = atomic_xchg(&sched->fw_events, 0); > struct panthor_device *ptdev = sched->ptdev; > > - mutex_lock(&sched->lock); > + guard(mutex)(&sched->lock); > + > + if (sched->destroyed) > + return; > > if (events & JOB_INT_GLOBAL_IF) { > sched_process_global_irq_locked(ptdev); > @@ -1778,8 +1788,6 @@ static void process_fw_events_work(struct work_struct *work) > sched_process_csg_irq_locked(ptdev, csg_id); > events &= ~BIT(csg_id); > } > - > - mutex_unlock(&sched->lock); > } > > /** > @@ -3882,6 +3890,7 @@ void panthor_sched_unplug(struct panthor_device *ptdev) > cancel_delayed_work_sync(&sched->tick_work); > > mutex_lock(&sched->lock); > + sched->destroyed = true; > if (sched->pm.has_ref) { > pm_runtime_put(ptdev->base.dev); > sched->pm.has_ref = false; > -- > 2.47.2 > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯