Re: [PATCH v1 1/1] usb: hcd: Bump local buffer size in rh_string()

[Greg Kroah-Hartman]

On Fri, Jan 17, 2025 at 03:42:27PM +0200, Andy Shevchenko wrote:
> On Fri, Jan 17, 2025 at 07:11:46AM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Jan 16, 2025 at 06:05:43PM +0200, Andy Shevchenko wrote:
> > > GCC is not happy about the buffer size:
> > > 
> > > drivers/usb/core/hcd.c:441:48: error: ‘%s’ directive output may be truncated writing up to 64 bytes into a region of size between 35 and 99 [-Werror=format-truncation=]
> > >   441 |                 snprintf (buf, sizeof buf, "%s %s %s", init_utsname()->sysname,
> > >       |                                                ^~
> > >   442 |                         init_utsname()->release, hcd->driver->description);
> > >       |                         ~~~~~~~~~~~~~~~~~~~~~~~
> > > 
> > > Bump the size to get it enough for the possible strings.
> 
> ...
> 
> > >  static unsigned
> > >  rh_string(int id, struct usb_hcd const *hcd, u8 *data, unsigned len)
> > >  {
> > > -	char buf[100];
> > > +	char buf[160];
> > >  	char const *s;
> > >  	static char const langids[4] = {4, USB_DT_STRING, 0x09, 0x04};
> > 
> > Worst case it's properly truncated so why do we need to worry about this
> > "warning"?
> 
> With CONFIG_WERROR=y it's a compilation error. My goal is to have
> i386_defconfig and x86_64_defconfig to be compiled with `make W=1`.

So you have to have W=1 enabled, right?  On my normal builds, with
CONFIG_WERROR=y enabled, I do not see this.

> > And what compiler version is giving that, I don't see that
> > here in my build testing.
> 
> `make W=1` (and be sure that CONFIG_WERROR=y).

Ah, ok, manual work here.

And I guess the error is right, ->sysname could be 64 and release can
also be 64 bytes long, so it would be truncated.

thanks,

greg k-h