On Mon, Sep 7, 2020 at 1:05 PM Bartosz Golaszewski <[email protected]> wrote: > On Fri, Sep 4, 2020 at 6:35 PM Andy Shevchenko > <[email protected]> wrote: > > On Fri, Sep 04, 2020 at 05:45:27PM +0200, Bartosz Golaszewski wrote: > > > From: Bartosz Golaszewski <[email protected]>
> > Doesn't mm/util.c provides us something like this? > > strndup_user()? > > > > Yes, there's both strndup_user() as well as strncpy_from_user(). The > problem is that they rely on the strings being NULL-terminated. This > is not guaranteed for debugfs file_operations write callbacks. We need > some helper that takes the minimum of bytes provided by userspace and > the buffer size and figure out how many bytes to actually copy IMO. Wouldn't this [1] approach work? [1]: https://elixir.bootlin.com/linux/v5.9-rc3/source/arch/x86/kernel/cpu/mtrr/if.c#L93 -- With Best Regards, Andy Shevchenko
