Re: [PATCH v3 1/2] uapi: fix __DECLARE_FLEX_ARRAY for C++

2023-09-15 Thread Kees Cook
On Tue, Sep 12, 2023 at 07:22:24PM +0300, Alexey Dobriyan wrote: > __DECLARE_FLEX_ARRAY(T, member) macro expands to > > struct { > struct {} __empty_member; > T member[]; > }; > > which is subtly wrong in C++ because sizeof(struct{}) is 1 not 0, > changing

[PATCH v3 1/2] uapi: fix __DECLARE_FLEX_ARRAY for C++

2023-09-12 Thread Alexey Dobriyan
__DECLARE_FLEX_ARRAY(T, member) macro expands to struct { struct {} __empty_member; T member[]; }; which is subtly wrong in C++ because sizeof(struct{}) is 1 not 0, changing UAPI structures layouts. This can be fixed by expanding to T memb