linux-kernel - Re: [PATCH net v3 2/3] rtase: Increase the size of ivec->name

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Message-ID: <20250423161658.GC2843373@horms.kernel.org>
Date: Wed, 23 Apr 2025 17:16:58 +0100
From: Simon Horman <horms@...nel.org>
To: Justin Lai <justinlai0215@...ltek.com>
Cc: "kuba@...nel.org" <kuba@...nel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"pabeni@...hat.com" <pabeni@...hat.com>,
	"andrew+netdev@...n.ch" <andrew+netdev@...n.ch>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Ping-Ke Shih <pkshih@...ltek.com>,
	Larry Chiu <larry.chiu@...ltek.com>,
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH net v3 2/3] rtase: Increase the size of ivec->name

On Wed, Apr 23, 2025 at 11:53:12AM +0000, Justin Lai wrote:
> > On Thu, Apr 17, 2025 at 04:56:58PM +0800, Justin Lai wrote:
> > > Fix the following compile warning reported by the kernel test robot by
> > > increasing the size of ivec->name.
> > >
> > > drivers/net/ethernet/realtek/rtase/rtase_main.c: In function 'rtase_open':
> > > >> drivers/net/ethernet/realtek/rtase/rtase_main.c:1117:52: warning:
> > > '%i' directive output may be truncated writing between 1 and 10 bytes
> > > into a region of size between 7 and 22 [-Wformat-truncation=]
> > >      snprintf(ivec->name, sizeof(ivec->name), "%s_int%i",
> > >                                                      ^~
> > >  drivers/net/ethernet/realtek/rtase/rtase_main.c:1117:45: note:
> > >  directive argument in the range [0, 2147483647]
> > >      snprintf(ivec->name, sizeof(ivec->name), "%s_int%i",
> > >                                               ^~~~~~~~~~
> > >  drivers/net/ethernet/realtek/rtase/rtase_main.c:1117:4: note:
> > >  'snprintf' output between 6 and 30 bytes into a destination of  size
> > > 26
> > >      snprintf(ivec->name, sizeof(ivec->name), "%s_int%i",
> > >      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >        tp->dev->name, i);
> > >        ~~~~~~~~~~~~~~~~~
> > 
> > Hi Justin,
> > 
> > Given that the type of i is u16, it's theoretical range of values is [0, 65536].
> > (I expect that in practice the range is significantly smaller.)
> > 
> > So the string representation of i should fit in the minumum of 7 bytes available
> > (only a maximum of 5 are needed).
> > 
> > And I do notice that newer compilers do not seem to warn about this.
> > 
> > So I don't really think this needs updating.
> > And if so, certainly not as a fix for 'net'.
> > 
> > Also, as an aside, as i is unsigned, the format specifier really ought to be %u
> > instead of %i. Not that it seems to make any difference here given the range of
> > values discussed above.
> > 
> > > Reported-by: kernel test robot <lkp@...el.com>
> > > Closes:
> > > https://lore.kernel.org/oe-kbuild-all/202503182158.nkAlbJWX-lkp@intel.
> > > com/
> > > Fixes: a36e9f5cfe9e ("rtase: Add support for a pci table in this
> > > module")
> > > Signed-off-by: Justin Lai <justinlai0215@...ltek.com>
> > 
> > --
> > pw-bot: changes-requested
> 
> Hi Simon,
> 
> Thank you for your reply. I will modify the format specifier to %u.
> Since the warning from the kernel test robot is a false positive, I
> will not address this warning, meaning I will not increase the size
> of ivec->name. This patch will be posted to net-next.

Thanks, sounds good to me.