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From: Andreas Schwab <schwab@linux-m68k.org>
To: Aleksa Sarai <cyphar@cyphar.com>
Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,
 from}_user helpers
References: <20190904201933.10736-1-cyphar@cyphar.com>
 <20190904201933.10736-2-cyphar@cyphar.com>
X-Yow: RELATIVES!!
Date: Thu, 05 Sep 2019 11:09:35 +0200
In-Reply-To: <20190904201933.10736-2-cyphar@cyphar.com> (Aleksa Sarai's
 message of "Thu, 5 Sep 2019 06:19:22 +1000")
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Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
 Peter Zijlstra <peterz@infradead.org>,
 Rasmus Villemoes <linux@rasmusvillemoes.dk>,
 Alexei Starovoitov <ast@kernel.org>, linux-kernel@vger.kernel.org,
 David Howells <dhowells@redhat.com>, linux-kselftest@vger.kernel.org,
 sparclinux@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
 linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
 Tycho Andersen <tycho@tycho.ws>, Aleksa Sarai <asarai@suse.de>,
 Jiri Olsa <jolsa@redhat.com>,
 Alexander Shishkin <alexander.shishkin@linux.intel.com>,
 Ingo Molnar <mingo@redhat.com>, linux-arm-kernel@lists.infradead.org,
 linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org,
 Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
 Jann Horn <jannh@google.com>, linuxppc-dev@lists.ozlabs.org,
 linux-m68k@lists.linux-m68k.org, Al Viro <viro@zeniv.linux.org.uk>,
 Andy Lutomirski <luto@kernel.org>, Shuah Khan <skhan@linuxfoundation.org>,
 Namhyung Kim <namhyung@kernel.org>, David Drysdale <drysdale@google.com>,
 Christian Brauner <christian@brauner.io>,
 "J. Bruce Fields" <bfields@fieldses.org>, linux-parisc@vger.kernel.org,
 linux-api@vger.kernel.org, Chanho Min <chanho.min@lge.com>,
 Jeff Layton <jlayton@kernel.org>, Oleg Nesterov <oleg@redhat.com>,
 Eric Biederman <ebiederm@xmission.com>, linux-alpha@vger.kernel.org,
 linux-fsdevel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
 Linus Torvalds <torvalds@linux-foundation.org>,
 containers@lists.linux-foundation.org
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 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

On Sep 05 2019, Aleksa Sarai <cyphar@cyphar.com> wrote:

> diff --git a/lib/struct_user.c b/lib/struct_user.c
> new file mode 100644
> index 000000000000..7301ab1bbe98
> --- /dev/null
> +++ b/lib/struct_user.c
> @@ -0,0 +1,182 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2019 SUSE LLC
> + * Copyright (C) 2019 Aleksa Sarai <cyphar@cyphar.com>
> + */
> +
> +#include <linux/types.h>
> +#include <linux/export.h>
> +#include <linux/uaccess.h>
> +#include <linux/kernel.h>
> +#include <linux/string.h>
> +
> +#define BUFFER_SIZE 64
> +
> +/*
> + * "memset(p, 0, size)" but for user space buffers. Caller must have already
> + * checked access_ok(p, size).
> + */
> +static int __memzero_user(void __user *p, size_t s)
> +{
> +	const char zeros[BUFFER_SIZE] = {};

Perhaps make that static?

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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"And now for something completely different."