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Message-ID: <874jwqfuh6.fsf@mpe.ellerman.id.au> Date: Thu, 29 Sep 2022 18:36:05 +1000 From: Michael Ellerman <mpe@...erman.id.au> To: Kees Cook <keescook@...omium.org>, Geert Uytterhoeven <geert@...ux-m68k.org> Cc: Vlastimil Babka <vbabka@...e.cz>, Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>, Andrew Morton <akpm@...ux-foundation.org>, Roman Gushchin <roman.gushchin@...ux.dev>, Hyeonggon Yoo <42.hyeyoo@...il.com>, Marco Elver <elver@...gle.com>, linux-mm@...ck.org, "Ruhl, Michael J" <michael.j.ruhl@...el.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Nick Desaulniers <ndesaulniers@...gle.com>, Alex Elder <elder@...nel.org>, Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>, Sumit Semwal <sumit.semwal@...aro.org>, Christian König <christian.koenig@....com>, Jesse Brandeburg <jesse.brandeburg@...el.com>, Daniel Micay <danielmicay@...il.com>, Yonghong Song <yhs@...com>, Miguel Ojeda <ojeda@...nel.org>, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, linux-btrfs@...r.kernel.org, linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org, linux-fsdevel@...r.kernel.org, intel-wired-lan@...ts.osuosl.org, dev@...nvswitch.org, x86@...nel.org, llvm@...ts.linux.dev, linux-hardening@...r.kernel.org Subject: Re: [PATCH v2 01/16] slab: Remove __malloc attribute from realloc functions Kees Cook <keescook@...omium.org> 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 <keescook@...omium.org> 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 <cl@...ux.com> >> > Cc: Pekka Enberg <penberg@...nel.org> >> > Cc: David Rientjes <rientjes@...gle.com> >> > Cc: Joonsoo Kim <iamjoonsoo.kim@....com> >> > Cc: Andrew Morton <akpm@...ux-foundation.org> >> > Cc: Vlastimil Babka <vbabka@...e.cz> >> > Cc: Roman Gushchin <roman.gushchin@...ux.dev> >> > Cc: Hyeonggon Yoo <42.hyeyoo@...il.com> >> > Cc: Marco Elver <elver@...gle.com> >> > Cc: linux-mm@...ck.org >> > Signed-off-by: Kees Cook <keescook@...omium.org> >> >> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: >> Remove __malloc attribute from realloc functions") in next-20220927. >> >> Noreply@...erman.id.au 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. cheers diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index f141a6f6b9f6..0717534f8364 100644 --- 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)
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