Hi Michael, On Thu, Sep 29, 2022 at 10:36 AM Michael Ellerman <[email protected]> wrote: > Kees Cook <[email protected]> writes: > > On Wed, Sep 28, 2022 at 09:26:15AM +0200, Geert Uytterhoeven wrote: > >> On Fri, Sep 23, 2022 at 10:35 PM Kees Cook <[email protected]> wrote: > >> > The __malloc attribute should not be applied to "realloc" functions, as > >> > the returned pointer may alias the storage of the prior pointer. Instead > >> > of splitting __malloc from __alloc_size, which would be a huge amount of > >> > churn, just create __realloc_size for the few cases where it is needed. > >> > > >> > Additionally removes the conditional test for __alloc_size__, which is > >> > always defined now. > >> > > >> > Cc: Christoph Lameter <[email protected]> > >> > Cc: Pekka Enberg <[email protected]> > >> > Cc: David Rientjes <[email protected]> > >> > Cc: Joonsoo Kim <[email protected]> > >> > Cc: Andrew Morton <[email protected]> > >> > Cc: Vlastimil Babka <[email protected]> > >> > Cc: Roman Gushchin <[email protected]> > >> > Cc: Hyeonggon Yoo <[email protected]> > >> > Cc: Marco Elver <[email protected]> > >> > Cc: [email protected] > >> > Signed-off-by: Kees Cook <[email protected]> > >> > >> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: > >> Remove __malloc attribute from realloc functions") in next-20220927. > >> > >> [email protected] reported all gcc8-based builds to fail > >> (e.g. [1], more at [2]): > >> > >> In file included from <command-line>: > >> ./include/linux/percpu.h: In function ‘__alloc_reserved_percpu’: > >> ././include/linux/compiler_types.h:279:30: error: expected > >> declaration specifiers before ‘__alloc_size__’ > >> #define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) > >> __malloc > >> ^~~~~~~~~~~~~~ > >> ./include/linux/percpu.h:120:74: note: in expansion of macro > >> ‘__alloc_size’ > >> [...] > >> > >> It's building fine with e.g. gcc-9 (which is my usual m68k cross-compiler). > >> Reverting this commit on next-20220927 fixes the issue. > >> > >> [1] http://kisskb.ellerman.id.au/kisskb/buildresult/14803908/ > >> [2] > >> http://kisskb.ellerman.id.au/kisskb/head/1bd8b75fe6adeaa89d02968bdd811ffe708cf839/ > > > > Eek! Thanks for letting me know. I'm confused about this -- > > __alloc_size__ wasn't optional in compiler_attributes.h -- but obviously > > I broke something! I'll go figure this out. > > This fixes it for me.
Kees submitted a similar patch 20 minutes before: https://lore.kernel.org/all/[email protected] > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -275,8 +275,13 @@ struct ftrace_likely_data { > * be performing a _reallocation_, as that may alias the existing pointer. > * For these, use __realloc_size(). > */ > -#define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc > -#define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) > +#ifdef __alloc_size__ > +# define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc > +# define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) > +#else > +# define __alloc_size(x, ...) __malloc > +# define __realloc_size(x, ...) > +#endif > > #ifndef asm_volatile_goto > #define asm_volatile_goto(x...) asm goto(x) Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected] In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
