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Date: Mon, 15 Apr 2024 15:12:17 +0200
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: William Hubbs <w.d.hubbs@gmail.com>,
	Chris Brannon <chris@the-brannons.com>,
	Kirk Reiser <kirk@reisers.ca>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Randy Dunlap <rdunlap@infradead.org>, speakup@linux-speakup.org,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] speakup: Fix sizeof() vs ARRAY_SIZE() bug
Message-ID: <20240415131217.t3zfjucclauc3rkz@begin>
Mail-Followup-To: Samuel Thibault <samuel.thibault@ens-lyon.org>,
	Dan Carpenter <dan.carpenter@linaro.org>,
	William Hubbs <w.d.hubbs@gmail.com>,
	Chris Brannon <chris@the-brannons.com>,
	Kirk Reiser <kirk@reisers.ca>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Randy Dunlap <rdunlap@infradead.org>, speakup@linux-speakup.org,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
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Dan Carpenter, le lun. 15 avril 2024 14:02:23 +0300, a ecrit:
> The "buf" pointer is an array of u16 values.  This code should be
> using ARRAY_SIZE() (which is 256) instead of sizeof() (which is 512),
> otherwise it can the still got out of bounds.
> 
> Fixes: c8d2f34ea96e ("speakup: Avoid crash on very long word")
> Cc: stable@vger.kernel.org
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org

Thanks!

> ---
>  drivers/accessibility/speakup/main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/accessibility/speakup/main.c b/drivers/accessibility/speakup/main.c
> index 736c2eb8c0f3..f677ad2177c2 100644
> --- a/drivers/accessibility/speakup/main.c
> +++ b/drivers/accessibility/speakup/main.c
> @@ -574,7 +574,7 @@ static u_long get_word(struct vc_data *vc)
>  	}
>  	attr_ch = get_char(vc, (u_short *)tmp_pos, &spk_attr);
>  	buf[cnt++] = attr_ch;
> -	while (tmpx < vc->vc_cols - 1 && cnt < sizeof(buf) - 1) {
> +	while (tmpx < vc->vc_cols - 1 && cnt < ARRAY_SIZE(buf) - 1) {
>  		tmp_pos += 2;
>  		tmpx++;
>  		ch = get_char(vc, (u_short *)tmp_pos, &temp);
> -- 
> 2.43.0
>