Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, Mar 8, 2018 at 5:35 PM, Linus Torvalds wrote: > I don't want to weaken the type enforcement, and I _thought_ you had > done that __builtin_types_compatible_p() to keep it in place. I thought so too (that originally came from Josh), but on removal, I was

Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, Mar 8, 2018 at 4:45 PM, Kees Cook wrote: > > Rasmus mentioned this too. What I said there was that I was shy to > make that change, since we already can't mix that kind of thing with > the existing min()/max() implementation. The existing min()/max() is > already

Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, Mar 8, 2018 at 3:48 PM, Linus Torvalds wrote: > On Thu, Mar 8, 2018 at 1:40 PM, Kees Cook wrote: >> +#define __min(t1, t2, x, y)\ >> + __builtin_choose_expr(__builtin_constant_p(x) &&

Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, Mar 8, 2018 at 1:40 PM, Kees Cook wrote: > +#define __min(t1, t2, x, y)\ > + __builtin_choose_expr(__builtin_constant_p(x) &&\ > + __builtin_constant_p(y) &&

Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, Mar 8, 2018 at 2:18 PM, Andrew Morton wrote: > On Thu, 8 Mar 2018 13:40:45 -0800 Kees Cook wrote: > >> When max() is used in stack array size calculations from literal values >> (e.g. "char foo[max(sizeof(struct1), sizeof(struct2))]", the

Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, 8 Mar 2018 13:40:45 -0800 Kees Cook wrote: > When max() is used in stack array size calculations from literal values > (e.g. "char foo[max(sizeof(struct1), sizeof(struct2))]", the compiler > thinks this is a dynamic calculation due to the single-eval logic, which >

Re: [PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

On Thu, 2018-03-08 at 13:40 -0800, Kees Cook wrote: > > +#define __min(t1, t2, x, y) \ > + __builtin_choose_expr(__builtin_constant_p(x) &&\ > + __builtin_constant_p(y) &&\ > +

[PATCH] kernel.h: Skip single-eval logic on literals in min()/max()

When max() is used in stack array size calculations from literal values (e.g. "char foo[max(sizeof(struct1), sizeof(struct2))]", the compiler thinks this is a dynamic calculation due to the single-eval logic, which is not needed in the literal case. This change removes several accidental stack