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Date:   Mon, 25 Oct 2021 14:43:55 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Jiasheng Jiang <jiasheng@iscas.ac.cn>
Cc:     mingo@redhat.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] sched: Fix implicit type conversion
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On Mon, Oct 25, 2021 at 12:19:37PM +0000, Jiasheng Jiang wrote:
> The variable 'n' is defined as ULONG. However in the cpumask_next(),
> it is used as INT.
> That is vulnerable and may cause overflow.
> For example, if the value of 'n' is (2^31 - 1), then it can pass the

That would need nr_cpu_ids to be that large. How's that going to happen?