On Fri, Jun 05, 2026 at 05:42:48PM +0200, Thorsten Blum wrote:
> On Fri, Jun 05, 2026 at 07:41:11AM +0300, Andy Shevchenko wrote:
> > On Thu, Jun 04, 2026 at 03:17:53PM +0200, Thorsten Blum wrote:
...
> > > strscpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
> >
> > This also has third argument fixed. Don't you want to change that?
>
> That doesn't work because boot_command_line, at least the declaration in
> linux/init.h, doesn't have a fixed size.
Ah, okay.
> > > #else
> > > if (builtin_cmdline[0]) {
> > > + size_t len = strnlen(builtin_cmdline, COMMAND_LINE_SIZE);
> > > +
> > > /* append boot loader cmdline to builtin */
> > > - strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
> > > - strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
> > > + snprintf(builtin_cmdline + len, COMMAND_LINE_SIZE - len, " %s",
> > > + boot_command_line);
> >
> > Hmm... Wouldn't GCC complain on this? (Build with `make W=1`.)
>
> No warnings with W=1. Why would GCC warn here?
Sometimes it complains if it can't prove the size of the string to fit the
destination. You said that there is no size for boot_command_line, I'm not
sure I understand how GCC proves that the above snprintf() won't ever truncate
the input.
> > > strscpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
> >
> > And this has also third argument.
>
> Same reason as above.
--
With Best Regards,
Andy Shevchenko
