linux-kernel - Re: [PATCH V2 5/5] Tools: hv: kvp: Fix a warning of buffer overflow with gcc 8.0.1

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Date:   Thu, 18 Oct 2018 09:32:31 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kys@...rosoft.com
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
        jasowang@...hat.com, sthemmin@...rosoft.com,
        Michael.H.Kelley@...rosoft.com, vkuznets@...hat.com,
        Haiyang Zhang <haiyangz@...rosoft.com>
Subject: Re: [PATCH V2 5/5] Tools: hv: kvp: Fix a warning of buffer overflow
 with gcc 8.0.1

On Thu, Oct 18, 2018 at 05:09:32AM +0000, kys@...uxonhyperv.com wrote:
> From: Dexuan Cui <decui@...rosoft.com>
> 
> The patch fixes:
> 
> hv_kvp_daemon.c: In function 'kvp_set_ip_info':
> hv_kvp_daemon.c:1305:2: note: 'snprintf' output between 41 and 4136 bytes
> into a destination of size 4096
> 
> The "(unsigned int)str_len" is to avoid:
> 
> hv_kvp_daemon.c:1309:30: warning: comparison of integer expressions of
> different signedness: 'int' and 'long unsigned int' [-Wsign-compare]
> 

Ugh...  Any tool with the most basic flow analysis would realize this
was a false positive.  We use at least three static analyzers which
catch signedness bugs.  Can we turn off GCC's warning on this until they
improve it a bit?

regards,
dan carpenter