linux-kernel - Re: [PATCH] accessibility: speakup: Fix incorrect string length computation in report_char_chartab

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Message-ID: <10d321d6-89ab-464e-971d-bb9635a5308f@moroto.mountain>
Date:   Wed, 6 Sep 2023 12:09:25 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     William Hubbs <w.d.hubbs@...il.com>,
        Chris Brannon <chris@...-brannons.com>,
        Kirk Reiser <kirk@...sers.ca>,
        Samuel Thibault <samuel.thibault@...-lyon.org>,
        Greg Kroah-Hartman <gregkh@...e.de>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        speakup@...ux-speakup.org
Subject: Re: [PATCH] accessibility: speakup: Fix incorrect string length
 computation in report_char_chartab_status()

On Mon, Sep 04, 2023 at 09:31:44PM +0200, Christophe JAILLET wrote:
> snprintf() returns the "number of characters which *would* be generated for
> the given input", not the size *really* generated.
> 
> In order to avoid too large values for 'len' (and potential negative
> values for "sizeof(buf) - (len - 1)") use scnprintf() instead of
> snprintf().
> 

A bunch of kernel-janitors mail didn't reach my inbox...  Like this
one.  So weird.

Reviewed-by: Dan Carpenter <dan.carpenter@...aro.org>

The impact of this bug is a WARN() btw.  snprintf() will refuse to
print negative bytes.

regards,
dan carpenter