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Message-ID: <Y2W3zEcMd82B0O1I@hyeyoo>
Date: Sat, 5 Nov 2022 10:09:32 +0900
From: Hyeonggon Yoo <42.hyeyoo@...il.com>
To: Kees Cook <keescook@...omium.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>, linux-mm@...ck.org,
David Gow <davidgow@...gle.com>,
Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
Guenter Roeck <linux@...ck-us.net>,
Andy Shevchenko <andriy.shevchenko@...el.com>,
Paolo Abeni <pabeni@...hat.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
linux-hardening@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH 3/6] slab: Provide functional __alloc_size() hints to
kmalloc_trace*()
On Fri, Nov 04, 2022 at 11:22:42AM -0700, Kees Cook wrote:
> On Thu, Nov 03, 2022 at 11:16:53PM +0900, Hyeonggon Yoo wrote:
> > On Tue, Nov 01, 2022 at 03:33:11PM -0700, Kees Cook wrote:
> > > Since GCC cannot apply the __alloc_size attributes to inlines[1], all
> > > allocator inlines need to explicitly call into extern functions that
> > > contain a size argument. Provide these wrappers that end up just
> > > ignoring the size argument for the actual allocation.
> > >
> > > This allows CONFIG_FORTIFY_SOURCE=y to see all various dynamic allocation
> > > sizes under GCC 12+ and all supported Clang versions.
> > >
> > > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96503
> > >
> > > Cc: Vlastimil Babka <vbabka@...e.cz>
> > > 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: Roman Gushchin <roman.gushchin@...ux.dev>
> > > Cc: Hyeonggon Yoo <42.hyeyoo@...il.com>
> > > Cc: linux-mm@...ck.org
> > > Signed-off-by: Kees Cook <keescook@...omium.org>
> > > ---
> > > include/linux/slab.h | 8 ++++++--
> > > mm/slab_common.c | 14 ++++++++++++++
> > > 2 files changed, 20 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/include/linux/slab.h b/include/linux/slab.h
> > > index 970e9504949e..051d86ca31a8 100644
> > > --- a/include/linux/slab.h
> > > +++ b/include/linux/slab.h
> > > @@ -442,6 +442,8 @@ static_assert(PAGE_SHIFT <= 20);
> > >
> > > void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
> > > void *kmem_cache_alloc(struct kmem_cache *s, gfp_t flags) __assume_slab_alignment __malloc;
> > > +void *kmem_cache_alloc_sized(struct kmem_cache *s, gfp_t flags, size_t size)
> > > + __assume_slab_alignment __alloc_size(3);
> > > void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
> > > gfp_t gfpflags) __assume_slab_alignment __malloc;
> > > void kmem_cache_free(struct kmem_cache *s, void *objp);
> > > @@ -469,6 +471,8 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignm
> > > __alloc_size(1);
> > > void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node) __assume_slab_alignment
> > > __malloc;
> > > +void *kmem_cache_alloc_node_sized(struct kmem_cache *s, gfp_t flags, int node, size_t size)
> > > + __assume_slab_alignment __alloc_size(4);
> > >
> > > #ifdef CONFIG_TRACING
> > > void *kmalloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
> > > @@ -482,7 +486,7 @@ void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
> > > static __always_inline __alloc_size(3)
> > > void *kmalloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
> > > {
> > > - void *ret = kmem_cache_alloc(s, flags);
> > > + void *ret = kmem_cache_alloc_sized(s, flags, size);
> > >
> > > ret = kasan_kmalloc(s, ret, size, flags);
> > > return ret;
> > > @@ -492,7 +496,7 @@ static __always_inline __alloc_size(4)
> > > void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
> > > int node, size_t size)
> > > {
> > > - void *ret = kmem_cache_alloc_node(s, gfpflags, node);
> > > + void *ret = kmem_cache_alloc_node_sized(s, gfpflags, node, size);
> > >
> > > ret = kasan_kmalloc(s, ret, size, gfpflags);
> > > return ret;
> > > diff --git a/mm/slab_common.c b/mm/slab_common.c
> > > index 33b1886b06eb..5fa547539a6a 100644
> > > --- a/mm/slab_common.c
> > > +++ b/mm/slab_common.c
> > > @@ -1457,6 +1457,20 @@ size_t ksize(const void *objp)
> > > }
> > > EXPORT_SYMBOL(ksize);
> > >
> > > +/* Wrapper so __alloc_size() can see the actual allocation size. */
> > > +void *kmem_cache_alloc_sized(struct kmem_cache *s, gfp_t flags, size_t size)
> > > +{
> > > + return kmem_cache_alloc(s, flags);
> > > +}
> > > +EXPORT_SYMBOL(kmem_cache_alloc_sized);
> > > +
> > > +/* Wrapper so __alloc_size() can see the actual allocation size. */
> > > +void *kmem_cache_alloc_node_sized(struct kmem_cache *s, gfp_t flags, int node, size_t size)
> > > +{
> > > + return kmem_cache_alloc_node(s, flags, node);
> > > +}
> > > +EXPORT_SYMBOL(kmem_cache_alloc_node_sized);
> >
> > The reason that we have two implementations of kmalloc_trace*
> > depending on CONFIG_TRACING is to save additional function call when
> > CONFIG_TRACING is not set.
> >
> > With this patch there is no reason to keep both.
> > So let's drop #ifdefs and use single implementation in mm/slab_common.c.
>
> Okay, I'll respin...
>
> --
> Kees Cook
Oh, it seems Vlastimil already did that.
Maybe simply drop this patch in next spin?
https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git/commit/?h=slab/for-6.1-rc4/fixes&id=eb4940d4adf590590a9d0c47e38d2799c2ff9670
Thanks!
--
Hyeonggon
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