linux-kernel - Re: [PATCH] mm/maccess.c: actually return -EFAULT from strncpy_from

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Message-ID: <5622B0AC.1050307@plumgrid.com>
Date:	Sat, 17 Oct 2015 13:33:48 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH] mm/maccess.c: actually return -EFAULT from
 strncpy_from_unsafe

On 10/17/15 1:20 PM, Rasmus Villemoes wrote:
> As far as I can tell, strncpy_from_unsafe never returns -EFAULT. ret
> is the result of a __copy_from_user_inatomic(), which is 0 for success
> and positive (in this case necessarily 1) for access error - it is
> never negative. So we were always returning the length of the,
> possibly truncated, destination string.
>
> Signed-off-by: Rasmus Villemoes<linux@...musvillemoes.dk>
> ---
> Probably not -stable-worthy. I can only find two callers, one of which
> ignores the return value.

good catch.
Acked-by: Alexei Starovoitov <ast@...nel.org>

cc-ing original authors where I copy pasted that part from.

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