linux-kernel - Re: [PATCH] HID: hid-debug: clean up snprintf() checks in hid_resolv

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Message-ID: <nycvar.YFH.7.76.2109221149310.15944@cbobk.fhfr.pm>
Date:   Wed, 22 Sep 2021 11:49:39 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Dan Carpenter <dan.carpenter@...cle.com>
cc:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] HID: hid-debug: clean up snprintf() checks in
 hid_resolv_usage()

On Thu, 16 Sep 2021, Dan Carpenter wrote:

> The snprintf() limits are complicated and slightly wrong when it does:
> 
> 	max(0, HID_DEBUG_BUFSIZE - len - 1)
> 
> The "- 1" should not be there.  It means we can't use the last
> byte of the buffer.  If we change the first snprintf() to scnprintf()
> then we can remove the max().
> 
> At the start of the function the strlen(buf) is going always going to
> be < HID_DEBUG_BUFSIZE so that is safe.  If it were > HID_DEBUG_BUFSIZE
> then that would result in a WARN().

Applied, thanks Dan.

-- 
Jiri Kosina
SUSE Labs