linux-kernel - Re: [PATCH] mm/kmemleak: fix the possible wrong memory scanning period

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Message-ID: <20210615093555.GA26027@arm.com>
Date:   Tue, 15 Jun 2021 10:35:56 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Yanfei Xu <yanfei.xu@...driver.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/kmemleak: fix the possible wrong memory scanning
 period

On Mon, Jun 14, 2021 at 01:40:22AM +0800, Yanfei Xu wrote:
> This commit contains 3 modifies:
> 
> 1.Convert the type of jiffies_scan_wait to "unsigned long".
> 
> 2.Use READ/WRITE_ONCE() for accessing "jiffies_scan_wait".
> 
> 3.Fix the possible wrong memory scanning period. If you set a large
> memory scanning period like blow, then the "secs" variable will be
> non-zero, however the value of "jiffies_scan_wait" will be zero.
> 
>     echo "scan=0x10000000" > /sys/kernel/debug/kmemleak
> 
> It is because the type of the msecs_to_jiffies()'s parameter is
> "unsigned int", and the "secs * 1000" is larger than its max value.
> This in turn leads a unexpected jiffies_scan_wait, maybe zero. We
> corret it by replacing kstrtoul() with kstrtouint(), and check the
> msecs to prevent it larger than UINT_MAX.
> 
> Signed-off-by: Yanfei Xu <yanfei.xu@...driver.com>

Acked-by: Catalin Marinas <catalin.marinas@....com>