On Tue, Oct 21, 2025 at 12:24:05PM -0700, Kees Cook wrote:
On Tue, Oct 21, 2025 at 11:54:47AM +0200, Peter Zijlstra wrote:
[...] Unfortunately, this annotation cannot be used for "void *" members (since such a member is considered a pointer to an incomplete type, and neither Clang nor GCC developers could be convinced otherwise[1], even in the face of the GNU extension that "void *" has size "1 byte" for pointer arithmetic). For "void *" members, we must use the coming "sized_by" attribute.
So why do we need both __counted_by_ptr() and this __sized_by(), won't one be good enough?
[...] Let me take another stab at it...
It seems this will be acceptable as long as it is gated by GNU extensions. GCC patch in progress. Clang PR here: https://github.com/llvm/llvm-project/pull/163698