linux-kernel - Re: [PATCH v6 2/3] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation

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Message-ID: <B9C50D0B-DCD9-41A2-895D-4899728AF605@kernel.org>
Date: Sat, 26 Jul 2025 16:19:18 -0700
From: Kees Cook <kees@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Bhupesh <bhupesh@...lia.com>, akpm@...ux-foundation.org,
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Subject: Re: [PATCH v6 2/3] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation



On July 26, 2025 10:50:55 AM PDT, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>, but
>
>On Thu, 24 Jul 2025 at 16:49, Kees Cook <kees@...nel.org> wrote:
>>
>> Why not switch all of these to get_task_comm()? It will correctly handle
>> the size check and NUL termination.
>
>I'd rather aim to get rid of get_task_comm() entirely.

That works for me! I just get twitchy around seeing memcpy used for strings. :) if we're gonna NUL after the memcpy, just use strscpy_pad().

>And guess what? We *have* that function. It's called "strscpy()". It
>already does the right thing, including passing in the size of a fixed
>array and just dealing with it the RightWay(tm). Add '_pad()' if that
>is the behavior you want, and now you *document* the fact that the
>result is padded.

Exactly. Let's see how much we can just replace with strscpy_pad(). It we have other use cases, we can handle those separately.

-Kees

-- 
Kees Cook