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Date: Sat, 28 Sep 2024 14:39:45 -0700
From: Kees Cook <kees@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vegard Nossum <vegard.nossum@oracle.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Allen Pais <apais@linux.microsoft.com>,
	Roman Kisel <romank@linux.microsoft.com>,
	Xiaoming Ni <nixiaoming@huawei.com>,
	Vijay Nag <nagvijay@microsoft.com>, linux-kernel@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH] coredump: Do not lock during 'comm' reporting
Message-ID: <202409281438.EAC4B88C@keescook>
References: <20240928210830.work.307-kees@kernel.org>
 <20240928143532.39559729f9eceee468358abe@linux-foundation.org>
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In-Reply-To: <20240928143532.39559729f9eceee468358abe@linux-foundation.org>

On Sat, Sep 28, 2024 at 02:35:32PM -0700, Andrew Morton wrote:
> On Sat, 28 Sep 2024 14:08:31 -0700 Kees Cook <kees@kernel.org> wrote:
> 
> > The 'comm' member will always be NUL terminated,
> 
> Why is this?  I thought this is only true if the caller holds task_lock()?

Because it's always written with strscpy_pad(). The final byte will
always be NUL. (And this has been true for a very long time.)

-- 
Kees Cook