linux-kernel - Re: [PATCH] sched/fair: Fix overflow in vruntime

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d8588f5d-bccc-4791-9d44-bd3e383d21b9@huawei.com>
Date: Thu, 10 Jul 2025 10:01:15 +0800
From: Zicheng Qu <quzicheng@...wei.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: <mingo@...hat.com>, <juri.lelli@...hat.com>, <vincent.guittot@...aro.org>,
	<dietmar.eggemann@....com>, <rostedt@...dmis.org>, <bsegall@...gle.com>,
	<mgorman@...e.de>, <vschneid@...hat.com>, <linux-kernel@...r.kernel.org>,
	<tanghui20@...wei.com>, <zhangqiao22@...wei.com>, <judy.chenhui@...wei.com>
Subject: Re: [PATCH] sched/fair: Fix overflow in vruntime_eligible() causing
 NULL return

Hi,

Based on LTS 6.6. I also looked at the code logic around 
vruntime_eligible() in the mainline. It seems that if 
vruntime_eligible() consistently returned false, this could lead to null 
pointer dereferences.

I'm wondering if it's feasible to adjust the handling of integer 
overflows within vruntime_eligible() the way shown in my patch, or if 
there's a specific design rationale behind directly comparing integers 
that are susceptible to overflow in the current implementation?

Thanks

On 7/9/2025 7:53 PM, Peter Zijlstra wrote:
> On Wed, Jul 09, 2025 at 09:38:29AM +0000, Zicheng Qu wrote:
>
>> The best approach should be to dig deep into why overflow occurs, which
>> attributes lead to the overflow, whether it is normal, and how to avoid
>> it.
> What kernel version are you seeing this on?
>