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Date: Sat, 08 Aug 2009 15:01:29 +0200
From: Alexander Koeppe <format_c@...ine.de>
To: roel.kluin@...il.com
CC: LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fat: Read buffer overflow
Roel Kluin schrieb:
> If len is less or equal to 0, this results in a read of s[-1].
>
> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> ---
> diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
> index 6f27853..114ff6d 100644
> --- a/fs/fat/namei_vfat.c
> +++ b/fs/fat/namei_vfat.c
> @@ -202,6 +202,9 @@ static inline int vfat_is_used_badchars(const wchar_t *s, int len)
> {
> int i;
>
> + if (len <= 0)
> + return -EINVAL;
> +
> for (i = 0; i < len; i++)
> if (vfat_bad_char(s[i]))
> return -EINVAL;
> --
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This seem to be a bit redundant code.
If len is 0 or less, the loop won't iterate even one time and hence
not read outside the buffer.
The only advantage is, that re function signals the invalid argument.
-- A.Koeppe
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