linux-kernel - Re: [PATCH] samples: user-trap: fix strict-aliasing warning

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Message-Id: <170776334482.2557794.95461406898503535.b4-ty@chromium.org>
Date: Mon, 12 Feb 2024 10:42:27 -0800
From: Kees Cook <keescook@...omium.org>
To: Tycho Andersen <tycho@...ho.pizza>,
	Arnd Bergmann <arnd@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
	Arnd Bergmann <arnd@...db.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] samples: user-trap: fix strict-aliasing warning

On Mon, 12 Feb 2024 12:17:31 +0100, Arnd Bergmann wrote:
> I started getting warnings for this one file, though I can't see what changed
> since it was originally introduced in commit fec7b6690541 ("samples: add an
> example of seccomp user trap").
> 
> samples/seccomp/user-trap.c: In function 'send_fd':
> samples/seccomp/user-trap.c:50:11: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
>    50 |         *((int *)CMSG_DATA(cmsg)) = fd;
>       |          ~^~~~~~~~~~~~~~~~~~~~~~~
> samples/seccomp/user-trap.c: In function 'recv_fd':
> samples/seccomp/user-trap.c:83:18: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
>    83 |         return *((int *)CMSG_DATA(cmsg));
>       |                 ~^~~~~~~~~~~~~~~~~~~~~~~
> 
> [...]

Applied to for-next/seccomp, thanks!

[1/1] samples: user-trap: fix strict-aliasing warning
      https://git.kernel.org/kees/c/9ad28ca5238d

Take care,

-- 
Kees Cook