linux-kernel - Re: [PATCH 3/6] [v2] hexagon: use generic strncpy/strnlen from

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Message-ID: <20210517061635.GA23581@lst.de>
Date:   Mon, 17 May 2021 08:16:35 +0200
From:   Christoph Hellwig <hch@....de>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     linux-arch@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Christoph Hellwig <hch@....de>,
        Al Viro <viro@...iv.linux.org.uk>,
        Vineet Gupta <vgupta@...opsys.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Brian Cain <bcain@...eaurora.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Sid Manning <sidneym@...eaurora.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>,
        linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org,
        uclinux-h8-devel@...ts.sourceforge.jp,
        linux-hexagon@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
        linux-riscv@...ts.infradead.org, linux-um@...ts.infradead.org
Subject: Re: [PATCH 3/6] [v2] hexagon: use generic strncpy/strnlen from_user

On Sat, May 15, 2021 at 12:18:00PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> Most per-architecture versions of these functions are broken in some form,
> and they are almost certainly slower than the generic code as well.
> 
> Remove the ones for hexagon and instead use the generic version.
> This custom version reads the data twice for strncpy() by doing an extra
> strnlen(), and it apparently lacks a check for user_addr_max().

I'd be tempted to just remove the first paragraph and reword the second
as:

Remove the hexagon implementation of strncpy/strnlen and instead use the
generic versions.  The hexago version of strncpy reads the data twice by
doing an extra strnlen(), and it apparently lacks a check for
user_addr_max().