On Wed, Feb 28, 2024 at 08:41:07AM +0000, Lukasz Luba wrote: > Hi Nathan and Kees, > > On 2/27/24 17:00, Kees Cook wrote: > > On Tue, Feb 27, 2024 at 05:47:44PM +0100, Daniel Lezcano wrote: > > > Ok my misunderstanding was I thought sizeof() was calling _bdos under the > > > hood, so when calling sizeof(flex_array), it was returning the computed > > > size > > > inferring from the __counted_by field. > > > > Yeah, sizeof() has a very limited scope. __builtin_object_size() has > > more flexibility (via the 2nd argument, "type"), but it was still > > compile-time only. __builtin_dynamic_object_size() was added to bring > > runtime evaluations into the mix (initially to support the alloc_size > > attribute, and now includes the counted_by attribute too). > > > > Thanks for your earlier emails explaining these stuff. > Do you have maybe some presentation about those features > for the kernel (ideally w/ a video from some conference)?
I think Kees's 2022 and 2023 talks at LPC are a good place to start: https://youtu.be/tQwv79i02ks?si=Nj9hpvmQwPB4K3Y4&t=452 https://youtu.be/OEFFqhP5sts?si=u6RnOP641S8FkouD&t=614 https://outflux.net/slides/2022/lpc/features.pdf https://outflux.net/slides/2023/lpc/features.pdf Cheers, Nathan
