Date: Wed, 14 Feb 2018 11:35:17 -0800 From: Matthew Wilcox <willy@...radead.org> To: Kees Cook <keescook@...omium.org> Cc: Andrew Morton <akpm@...ux-foundation.org>, Matthew Wilcox <mawilcox@...rosoft.com>, Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, Kernel Hardening <kernel-hardening@...ts.openwall.com>, Julia Lawall <julia.lawall@...6.fr>, cocci@...teme.lip6.fr Subject: Re: [PATCH 2/2] mm: Add kvmalloc_ab_c and kvzalloc_struct On Wed, Feb 14, 2018 at 11:22:38AM -0800, Kees Cook wrote: > > +/** > > + * kvmalloc_ab_c() - Allocate memory. > > Longer description, maybe? "Allocate a *b + c bytes of memory"? Done! > > + * @n: Number of elements. > > + * @size: Size of each element (should be constant). > > + * @c: Size of header (should be constant). > > If these should be constant, should we mark them as "const"? Or WARN > if __builtin_constant_p() isn't true? It's only less efficient if they're not const. Theoretically they could be variable ... and I've been bitten by __builtin_constant_p() recently (gcc bug 83653 which I still don't really understand). > > + * @gfp: Memory allocation flags. > > + * > > + * Use this function to allocate @n * @size + @c bytes of memory. This > > + * function is safe to use when @n is controlled from userspace; it will > > + * return %NULL if the required amount of memory cannot be allocated. > > + * Use kvfree() to free the allocated memory. > > + * > > + * The kvzalloc_hdr_arr() function is easier to use as it has typechecking > > renaming typo? Should this be "kvzalloc_struct()"? Urgh, yes. I swear I searched for it ... must've typoed my search string. Anyway, fixed, because kvzalloc_hdr_arr() wasn't a good name. > > +#define kvzalloc_ab_c(a, b, c, gfp) kvmalloc_ab_c(a, b, c, gfp | __GFP_ZERO) > > Nit: "(gfp) | __GFP_ZERO" just in case of insane usage. Fixed! > It might be nice to include another patch that replaces some of the > existing/common uses of a*b+c with the new function... Sure! I have a few examples in my tree, I just didn't want to complicate things by sending a patch that crossed dozens of maintainer trees.
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