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]>
---
include/linux/compiler_types.h | 13 +++++--------
include/linux/slab.h | 12 ++++++------
mm/slab_common.c | 4 ++--
3 files changed, 13 insertions(+), 16 deletions(-)
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 4f2a819fd60a..f141a6f6b9f6 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -271,15 +271,12 @@ struct ftrace_likely_data {
/*
* Any place that could be marked with the "alloc_size" attribute is also
- * a place to be marked with the "malloc" attribute. Do this as part of the
- * __alloc_size macro to avoid redundant attributes and to avoid missing a
- * __malloc marking.
+ * a place to be marked with the "malloc" attribute, except those that may
+ * be performing a _reallocation_, as that may alias the existing pointer.
+ * For these, use __realloc_size().
*/
-#ifdef __alloc_size__
-# define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
-#else
-# define __alloc_size(x, ...) __malloc
-#endif
+#define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
+#define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__)
#ifndef asm_volatile_goto
#define asm_volatile_goto(x...) asm goto(x)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 0fefdf528e0d..41bd036e7551 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -184,7 +184,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
/*
* Common kmalloc functions provided by all allocators
*/
-void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
+void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
void kfree(const void *objp);
void kfree_sensitive(const void *objp);
size_t __ksize(const void *objp);
@@ -647,10 +647,10 @@ static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_
* @new_size: new size of a single member of the array
* @flags: the type of memory to allocate (see kmalloc)
*/
-static inline __alloc_size(2, 3) void * __must_check krealloc_array(void *p,
- size_t new_n,
- size_t new_size,
- gfp_t flags)
+static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
+ size_t new_n,
+ size_t new_size,
+ gfp_t flags)
{
size_t bytes;
@@ -774,7 +774,7 @@ static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t fla
}
extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
- __alloc_size(3);
+ __realloc_size(3);
extern void kvfree(const void *addr);
extern void kvfree_sensitive(const void *addr, size_t len);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 17996649cfe3..457671ace7eb 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1134,8 +1134,8 @@ module_init(slab_proc_init);
#endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
-static __always_inline void *__do_krealloc(const void *p, size_t new_size,
- gfp_t flags)
+static __always_inline __realloc_size(2) void *
+__do_krealloc(const void *p, size_t new_size, gfp_t flags)
{
void *ret;
size_t ks;
--
2.34.1
Hi Kees,
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/
> ---
> include/linux/compiler_types.h | 13 +++++--------
> include/linux/slab.h | 12 ++++++------
> mm/slab_common.c | 4 ++--
> 3 files changed, 13 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index 4f2a819fd60a..f141a6f6b9f6 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -271,15 +271,12 @@ struct ftrace_likely_data {
>
> /*
> * Any place that could be marked with the "alloc_size" attribute is also
> - * a place to be marked with the "malloc" attribute. Do this as part of the
> - * __alloc_size macro to avoid redundant attributes and to avoid missing a
> - * __malloc marking.
> + * a place to be marked with the "malloc" attribute, except those that may
> + * be performing a _reallocation_, as that may alias the existing pointer.
> + * For these, use __realloc_size().
> */
> -#ifdef __alloc_size__
> -# define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
> -#else
> -# define __alloc_size(x, ...) __malloc
> -#endif
> +#define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
> +#define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__)
>
> #ifndef asm_volatile_goto
> #define asm_volatile_goto(x...) asm goto(x)
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 0fefdf528e0d..41bd036e7551 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -184,7 +184,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
> /*
> * Common kmalloc functions provided by all allocators
> */
> -void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
> +void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
> void kfree(const void *objp);
> void kfree_sensitive(const void *objp);
> size_t __ksize(const void *objp);
> @@ -647,10 +647,10 @@ static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_
> * @new_size: new size of a single member of the array
> * @flags: the type of memory to allocate (see kmalloc)
> */
> -static inline __alloc_size(2, 3) void * __must_check krealloc_array(void *p,
> - size_t new_n,
> - size_t new_size,
> - gfp_t flags)
> +static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
> + size_t new_n,
> + size_t new_size,
> + gfp_t flags)
> {
> size_t bytes;
>
> @@ -774,7 +774,7 @@ static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t fla
> }
>
> extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
> - __alloc_size(3);
> + __realloc_size(3);
> extern void kvfree(const void *addr);
> extern void kvfree_sensitive(const void *addr, size_t len);
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 17996649cfe3..457671ace7eb 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1134,8 +1134,8 @@ module_init(slab_proc_init);
>
> #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
>
> -static __always_inline void *__do_krealloc(const void *p, size_t new_size,
> - gfp_t flags)
> +static __always_inline __realloc_size(2) void *
> +__do_krealloc(const void *p, size_t new_size, gfp_t flags)
> {
> void *ret;
> size_t ks;
> --
> 2.34.1
>
--
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
On 9/28/22 09:26, Geert Uytterhoeven wrote:
> Hi Kees,
>
> 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.
So IIUC it was wrong to remove the #ifdefs?
> [1] http://kisskb.ellerman.id.au/kisskb/buildresult/14803908/
> [2] http://kisskb.ellerman.id.au/kisskb/head/1bd8b75fe6adeaa89d02968bdd811ffe708cf839/
>
>
>
>> ---
>> include/linux/compiler_types.h | 13 +++++--------
>> include/linux/slab.h | 12 ++++++------
>> mm/slab_common.c | 4 ++--
>> 3 files changed, 13 insertions(+), 16 deletions(-)
>>
>> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
>> index 4f2a819fd60a..f141a6f6b9f6 100644
>> --- a/include/linux/compiler_types.h
>> +++ b/include/linux/compiler_types.h
>> @@ -271,15 +271,12 @@ struct ftrace_likely_data {
>>
>> /*
>> * Any place that could be marked with the "alloc_size" attribute is also
>> - * a place to be marked with the "malloc" attribute. Do this as part of the
>> - * __alloc_size macro to avoid redundant attributes and to avoid missing a
>> - * __malloc marking.
>> + * a place to be marked with the "malloc" attribute, except those that may
>> + * be performing a _reallocation_, as that may alias the existing pointer.
>> + * For these, use __realloc_size().
>> */
>> -#ifdef __alloc_size__
>> -# define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
>> -#else
>> -# define __alloc_size(x, ...) __malloc
>> -#endif
>> +#define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
>> +#define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__)
>>
>> #ifndef asm_volatile_goto
>> #define asm_volatile_goto(x...) asm goto(x)
>> diff --git a/include/linux/slab.h b/include/linux/slab.h
>> index 0fefdf528e0d..41bd036e7551 100644
>> --- a/include/linux/slab.h
>> +++ b/include/linux/slab.h
>> @@ -184,7 +184,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
>> /*
>> * Common kmalloc functions provided by all allocators
>> */
>> -void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
>> +void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
>> void kfree(const void *objp);
>> void kfree_sensitive(const void *objp);
>> size_t __ksize(const void *objp);
>> @@ -647,10 +647,10 @@ static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_
>> * @new_size: new size of a single member of the array
>> * @flags: the type of memory to allocate (see kmalloc)
>> */
>> -static inline __alloc_size(2, 3) void * __must_check krealloc_array(void *p,
>> - size_t new_n,
>> - size_t new_size,
>> - gfp_t flags)
>> +static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
>> + size_t new_n,
>> + size_t new_size,
>> + gfp_t flags)
>> {
>> size_t bytes;
>>
>> @@ -774,7 +774,7 @@ static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t fla
>> }
>>
>> extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
>> - __alloc_size(3);
>> + __realloc_size(3);
>> extern void kvfree(const void *addr);
>> extern void kvfree_sensitive(const void *addr, size_t len);
>>
>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>> index 17996649cfe3..457671ace7eb 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -1134,8 +1134,8 @@ module_init(slab_proc_init);
>>
>> #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
>>
>> -static __always_inline void *__do_krealloc(const void *p, size_t new_size,
>> - gfp_t flags)
>> +static __always_inline __realloc_size(2) void *
>> +__do_krealloc(const void *p, size_t new_size, gfp_t flags)
>> {
>> void *ret;
>> size_t ks;
>> --
>> 2.34.1
>>
>
>
> --
> 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
On Wed, Sep 28, 2022 at 09:26:15AM +0200, Geert Uytterhoeven wrote:
> Hi Kees,
>
> 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.
-Kees
--
Kees Cook
On 9/28/22 19:13, Kees Cook wrote:
> On Wed, Sep 28, 2022 at 09:26:15AM +0200, Geert Uytterhoeven wrote:
>> Hi Kees,
>>
>> 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.
Even in latest next I can see at the end of include/linux/compiler-gcc.h
/*
* Prior to 9.1, -Wno-alloc-size-larger-than (and therefore the "alloc_size"
* attribute) do not work, and must be disabled.
*/
#if GCC_VERSION < 90100
#undef __alloc_size__
#endif
> -Kees
>
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.
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)
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
On Fri, Sep 23, 2022 at 01:28:07PM -0700, Kees Cook 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]>
> ---
> include/linux/compiler_types.h | 13 +++++--------
> include/linux/slab.h | 12 ++++++------
> mm/slab_common.c | 4 ++--
> 3 files changed, 13 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index 4f2a819fd60a..f141a6f6b9f6 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -271,15 +271,12 @@ struct ftrace_likely_data {
>
> /*
> * Any place that could be marked with the "alloc_size" attribute is also
> - * a place to be marked with the "malloc" attribute. Do this as part of the
> - * __alloc_size macro to avoid redundant attributes and to avoid missing a
> - * __malloc marking.
> + * a place to be marked with the "malloc" attribute, except those that may
> + * be performing a _reallocation_, as that may alias the existing pointer.
> + * For these, use __realloc_size().
> */
> -#ifdef __alloc_size__
> -# define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
> -#else
> -# define __alloc_size(x, ...) __malloc
> -#endif
> +#define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
> +#define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__)
>
> #ifndef asm_volatile_goto
> #define asm_volatile_goto(x...) asm goto(x)
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 0fefdf528e0d..41bd036e7551 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -184,7 +184,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
> /*
> * Common kmalloc functions provided by all allocators
> */
> -void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
> +void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
> void kfree(const void *objp);
> void kfree_sensitive(const void *objp);
> size_t __ksize(const void *objp);
> @@ -647,10 +647,10 @@ static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_
> * @new_size: new size of a single member of the array
> * @flags: the type of memory to allocate (see kmalloc)
> */
> -static inline __alloc_size(2, 3) void * __must_check krealloc_array(void *p,
> - size_t new_n,
> - size_t new_size,
> - gfp_t flags)
> +static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
> + size_t new_n,
> + size_t new_size,
> + gfp_t flags)
> {
> size_t bytes;
>
> @@ -774,7 +774,7 @@ static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t fla
> }
>
> extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
> - __alloc_size(3);
> + __realloc_size(3);
> extern void kvfree(const void *addr);
> extern void kvfree_sensitive(const void *addr, size_t len);
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 17996649cfe3..457671ace7eb 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1134,8 +1134,8 @@ module_init(slab_proc_init);
>
> #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
>
> -static __always_inline void *__do_krealloc(const void *p, size_t new_size,
> - gfp_t flags)
> +static __always_inline __realloc_size(2) void *
> +__do_krealloc(const void *p, size_t new_size, gfp_t flags)
> {
> void *ret;
> size_t ks;
> --
> 2.34.1
>
This is now squashed with later one. (so undefined __alloc_size__ issues are fixed)
for the latest version of this patch:
Looks good to me,
Acked-by: Hyeonggon Yoo <[email protected]>
--
Thanks,
Hyeonggon