netdev - Re: [PATCH v2 iproute2] ifstat: convert sprintf to snprintf

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Message-ID: <1de98d9d-7a7c-4e84-85b8-f28055210ee2@suse.de>
Date: Sun, 11 Feb 2024 21:10:00 +0300
From: Denis Kirjanov <dkirjanov@...e.de>
To: Stephen Hemminger <stephen@...workplumber.org>
Cc: Denis Kirjanov <kirjanov@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2 iproute2] ifstat: convert sprintf to snprintf



On 2/11/24 20:18, Stephen Hemminger wrote:
> On Sun, 11 Feb 2024 11:39:13 +0300
> Denis Kirjanov <dkirjanov@...e.de> wrote:
> 
>> On 2/10/24 23:33, Stephen Hemminger wrote:
>>> On Fri,  2 Feb 2024 04:35:27 -0500
>>> Denis Kirjanov <kirjanov@...il.com> wrote:
>>>   
>>>> Use snprintf to print only valid data
>>>>
>>>> v2: adjust formatting
>>>>
>>>> Signed-off-by: Denis Kirjanov <dkirjanov@...e.de>
>>>> ---  
>>>
>>> Tried this but compile failed
>>>
>>> ifstat.c:896:2: warning: 'snprintf' size argument is too large; destination buffer has size 107, but size argument is 108 [-Wfortify-source]
>>>         snprintf(sun.sun_path + 1, sizeof(sun.sun_path), "ifstat%d", getuid());  
>>
>> Right, this is addressed in the patch with scnprintf
>>  
> 
> But I see no need to convert to scnprintf(). Scnprintf is about the return value
> and almost nowhere in iproute2 uses the return value and those that to look at the
> return value are checking for beyond buffer. Plus if you convert to scnprintf you
> lose lots of the fortify and other analyzer checking.

the last line makes sense.

> 
> Bottom line scnprintf() makes sense in kernel but not iproute2.

I'll push the next version of a patch with snprintf then.
Thanks!