linux-kernel - Re: [PATCH v1 1/1] usb: Add checks for snprintf() calls in usb_alloc

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Message-ID: <ab7c2f42-f566-4c7b-b0ba-6f7446617e85@rowland.harvard.edu>
Date: Sat, 19 Apr 2025 14:23:32 -0400
From: Alan Stern <stern@...land.harvard.edu>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v1 1/1] usb: Add checks for snprintf() calls in
 usb_alloc_dev()

On Sat, Apr 19, 2025 at 07:27:08PM +0300, Andy Shevchenko wrote:
> On Fri, Mar 21, 2025 at 06:49:49PM +0200, Andy Shevchenko wrote:
> > When creating a device path in the driver the snprintf() takes
> > up to 16 characters long argument along with the additional up to
> > 12 characters for the signed integer (as it can't see the actual limits)
> > and tries to pack this into 16 bytes array. GCC complains about that
> > when build with `make W=1`:
> > 
> >   drivers/usb/core/usb.c:705:25: note: ‘snprintf’ output between 3 and 28 bytes into a destination of size 16
> > 
> > Since everything works until now, let's just check for the potential
> > buffer overflow and bail out. It is most likely a never happen situation,
> > but at least it makes GCC happy.
> 
> Any comments anybody?

It's not a hot path; the extra check won't hurt anything.

Acked-by: Alan Stern <stern@...land.harvard.edu>

Alan Stern