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From: Kees Cook <keescook@chromium.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-kernel@vger.kernel.org,
	Daniel Micay <danielmicay@gmail.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, Joe Perches <joe@perches.com>,
	Miguel Ojeda <ojeda@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Andy Whitcroft <apw@canonical.com>,
	Dwaipayan Ray <dwaipayanray1@gmail.com>,
	Lukas Bulwahn <lukas.bulwahn@gmail.com>,
	Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2 4/7] slab: Add __alloc_size attributes for better bounds checking
Date: Wed, 22 Sep 2021 15:41:19 -0700	[thread overview]
Message-ID: <202109211608.B9B6DEE@keescook> (raw)
In-Reply-To: <CAKwvOdmxRMcwKtWt+FogVY8iXn=vQ+0AZ36maJP2LbSdo_NNjg@mail.gmail.com>

On Wed, Aug 25, 2021 at 02:31:34PM -0700, Nick Desaulniers wrote:
> On Wed, Aug 18, 2021 at 2:40 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > As already done in GrapheneOS, add the __alloc_size attribute for
> > regular kmalloc interfaces, to provide additional hinting for better
> > bounds checking, assisting CONFIG_FORTIFY_SOURCE and other compiler
> > optimizations.
> >
> > Co-developed-by: Daniel Micay <danielmicay@gmail.com>
> > Signed-off-by: Daniel Micay <danielmicay@gmail.com>
> > Cc: Christoph Lameter <cl@linux.com>
> > Cc: Pekka Enberg <penberg@kernel.org>
> > Cc: David Rientjes <rientjes@google.com>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Vlastimil Babka <vbabka@suse.cz>
> > Cc: linux-mm@kvack.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> This is a good start, so
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Thanks!

> Do we also want to attribute:
> * __kmalloc_index

This is just the bucketizer (it returns "int" for the kmalloc bucket).

> * kmem_cache_free_bulk

Not an allocator.

> * kmem_cache_alloc_bulk

This allocates a list of pointers, where "size" is the length of the
list.

> * kmalloc_order
> * kmalloc_order_trace
> * kmalloc_large

Yes, these should be marked, good point.

> * kmalloc_node

This was already marked.

> * kmem_cache_alloc_trace
> * __kmalloc_track_caller
> * __kmalloc_node_track_caller

Yeah, these might get passed through in LTO situations. I'll add them.

> * kmalloc_array_node

I'll add this -- I thought it was already here but it got missed.

Thanks!

-Kees

> 
> > ---
> >  include/linux/slab.h | 20 ++++++++++++++++++--
> >  1 file changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/slab.h b/include/linux/slab.h
> > index 10fd0a8c816a..6ce826d8194d 100644
> > --- a/include/linux/slab.h
> > +++ b/include/linux/slab.h
> > @@ -181,7 +181,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
> >  /*
> >   * Common kmalloc functions provided by all allocators
> >   */
> > -__must_check
> > +__must_check __alloc_size(2)
> >  void *krealloc(const void *objp, size_t new_size, gfp_t flags);
> >  void kfree(const void *objp);
> >  void kfree_sensitive(const void *objp);
> > @@ -426,6 +426,7 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
> >  #define kmalloc_index(s) __kmalloc_index(s, true)
> >  #endif /* !CONFIG_SLOB */
> >
> > +__alloc_size(1)
> >  void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc;
> >  void *kmem_cache_alloc(struct kmem_cache *s, gfp_t flags) __assume_kmalloc_alignment __malloc;
> >  void kmem_cache_free(struct kmem_cache *s, void *objp);
> > @@ -450,6 +451,7 @@ static __always_inline void kfree_bulk(size_t size, void **p)
> >  }
> >
> >  #ifdef CONFIG_NUMA
> > +__alloc_size(1)
> >  void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_slab_alignment __malloc;
> >  void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node)
> >                             __assume_slab_alignment __malloc;
> > @@ -574,6 +576,7 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
> >   *     Try really hard to succeed the allocation but fail
> >   *     eventually.
> >   */
> > +__alloc_size(1)
> >  static __always_inline void *kmalloc(size_t size, gfp_t flags)
> >  {
> >         if (__builtin_constant_p(size)) {
> > @@ -596,6 +599,7 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags)
> >         return __kmalloc(size, flags);
> >  }
> >
> > +__alloc_size(1)
> >  static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
> >  {
> >  #ifndef CONFIG_SLOB
> > @@ -620,6 +624,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
> >   * @size: element size.
> >   * @flags: the type of memory to allocate (see kmalloc).
> >   */
> > +__alloc_size(1, 2)
> >  static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
> >  {
> >         size_t bytes;
> > @@ -638,7 +643,7 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
> >   * @new_size: new size of a single member of the array
> >   * @flags: the type of memory to allocate (see kmalloc)
> >   */
> > -__must_check
> > +__must_check __alloc_size(2, 3)
> >  static inline void *krealloc_array(void *p, size_t new_n, size_t new_size,
> >                                    gfp_t flags)
> >  {
> > @@ -656,6 +661,7 @@ static inline void *krealloc_array(void *p, size_t new_n, size_t new_size,
> >   * @size: element size.
> >   * @flags: the type of memory to allocate (see kmalloc).
> >   */
> > +__alloc_size(1, 2)
> >  static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
> >  {
> >         return kmalloc_array(n, size, flags | __GFP_ZERO);
> > @@ -685,6 +691,7 @@ static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
> >         return __kmalloc_node(bytes, flags, node);
> >  }
> >
> > +__alloc_size(1, 2)
> >  static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
> >  {
> >         return kmalloc_array_node(n, size, flags | __GFP_ZERO, node);
> > @@ -718,6 +725,7 @@ static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
> >   * @size: how many bytes of memory are required.
> >   * @flags: the type of memory to allocate (see kmalloc).
> >   */
> > +__alloc_size(1)
> >  static inline void *kzalloc(size_t size, gfp_t flags)
> >  {
> >         return kmalloc(size, flags | __GFP_ZERO);
> > @@ -729,25 +737,31 @@ static inline void *kzalloc(size_t size, gfp_t flags)
> >   * @flags: the type of memory to allocate (see kmalloc).
> >   * @node: memory node from which to allocate
> >   */
> > +__alloc_size(1)
> >  static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
> >  {
> >         return kmalloc_node(size, flags | __GFP_ZERO, node);
> >  }
> >
> > +__alloc_size(1)
> >  extern void *kvmalloc_node(size_t size, gfp_t flags, int node);
> > +__alloc_size(1)
> >  static inline void *kvmalloc(size_t size, gfp_t flags)
> >  {
> >         return kvmalloc_node(size, flags, NUMA_NO_NODE);
> >  }
> > +__alloc_size(1)
> >  static inline void *kvzalloc_node(size_t size, gfp_t flags, int node)
> >  {
> >         return kvmalloc_node(size, flags | __GFP_ZERO, node);
> >  }
> > +__alloc_size(1)
> >  static inline void *kvzalloc(size_t size, gfp_t flags)
> >  {
> >         return kvmalloc(size, flags | __GFP_ZERO);
> >  }
> >
> > +__alloc_size(1, 2)
> >  static inline void *kvmalloc_array(size_t n, size_t size, gfp_t flags)
> >  {
> >         size_t bytes;
> > @@ -758,11 +772,13 @@ static inline void *kvmalloc_array(size_t n, size_t size, gfp_t flags)
> >         return kvmalloc(bytes, flags);
> >  }
> >
> > +__alloc_size(1, 2)
> >  static inline void *kvcalloc(size_t n, size_t size, gfp_t flags)
> >  {
> >         return kvmalloc_array(n, size, flags | __GFP_ZERO);
> >  }
> >
> > +__alloc_size(3)
> >  extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize,
> >                 gfp_t flags);
> >  extern void kvfree(const void *addr);
> > --
> 
> -- 
> Thanks,
> ~Nick Desaulniers

-- 
Kees Cook

  reply	other threads:[~2021-09-22 22:41 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18 21:40 [PATCH v2 0/7] Add __alloc_size() " Kees Cook
2021-08-18 21:40 ` [PATCH v2 1/7] Compiler Attributes: " Kees Cook
2021-08-18 21:51   ` Nathan Chancellor
2021-08-18 23:19   ` Andrew Morton
2021-08-19  7:06     ` Kees Cook
2021-08-19  0:04   ` Miguel Ojeda
2021-08-18 21:40 ` [PATCH v2 2/7] checkpatch: Add __alloc_size() to known $Attribute Kees Cook
2021-08-18 21:40 ` [PATCH v2 3/7] slab: Clean up function declarations Kees Cook
2021-08-18 21:40 ` [PATCH v2 4/7] slab: Add __alloc_size attributes for better bounds checking Kees Cook
2021-08-19  8:27   ` Rasmus Villemoes
2021-08-25 21:31   ` Nick Desaulniers
2021-09-22 22:41     ` Kees Cook [this message]
2021-08-18 21:40 ` [PATCH v2 5/7] mm/page_alloc: " Kees Cook
2021-08-18 21:40 ` [PATCH v2 6/7] percpu: " Kees Cook
2021-08-19  0:42   ` Dennis Zhou
2021-08-19  3:36     ` Kees Cook
2021-08-19 14:12       ` Dennis Zhou
2021-08-20  5:11   ` Andrew Morton
2021-08-20  5:27     ` Kees Cook
2021-08-18 21:40 ` [PATCH v2 7/7] mm/vmalloc: " Kees Cook

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