| Message ID | 20220923202822.2667581-2-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | slab: Introduce kmalloc_size_roundup() | expand |
Hi Kees, On Fri, Sep 23, 2022 at 10:35 PM Kees Cook <keescook@chromium.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@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: Roman Gushchin <roman.gushchin@linux.dev> > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Cc: Marco Elver <elver@google.com> > Cc: linux-mm@kvack.org > Signed-off-by: Kees Cook <keescook@chromium.org> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: Remove __malloc attribute from realloc functions") in next-20220927. Noreply@ellerman.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/ > --- > 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 -- geert@linux-m68k.org 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 <keescook@chromium.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@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: Roman Gushchin <roman.gushchin@linux.dev> >> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> >> Cc: Marco Elver <elver@google.com> >> Cc: linux-mm@kvack.org >> Signed-off-by: Kees Cook <keescook@chromium.org> > > Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: > Remove __malloc attribute from realloc functions") in next-20220927. > > Noreply@ellerman.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. 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 -- geert@linux-m68k.org > > 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 <keescook@chromium.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@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: Roman Gushchin <roman.gushchin@linux.dev> > > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> > > Cc: Marco Elver <elver@google.com> > > Cc: linux-mm@kvack.org > > Signed-off-by: Kees Cook <keescook@chromium.org> > > Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: > Remove __malloc attribute from realloc functions") in next-20220927. > > Noreply@ellerman.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. -Kees
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 <keescook@chromium.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@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: Roman Gushchin <roman.gushchin@linux.dev> >>> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> >>> Cc: Marco Elver <elver@google.com> >>> Cc: linux-mm@kvack.org >>> Signed-off-by: Kees Cook <keescook@chromium.org> >> >> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: >> Remove __malloc attribute from realloc functions") in next-20220927. >> >> Noreply@ellerman.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. 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 <keescook@chromium.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@chromium.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@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: Roman Gushchin <roman.gushchin@linux.dev> >> > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> >> > Cc: Marco Elver <elver@google.com> >> > Cc: linux-mm@kvack.org >> > Signed-off-by: Kees Cook <keescook@chromium.org> >> >> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: >> Remove __malloc attribute from realloc functions") in next-20220927. >> >> Noreply@ellerman.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)
Hi Michael, On Thu, Sep 29, 2022 at 10:36 AM Michael Ellerman <mpe@ellerman.id.au> wrote: > Kees Cook <keescook@chromium.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@chromium.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@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: Roman Gushchin <roman.gushchin@linux.dev> > >> > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> > >> > Cc: Marco Elver <elver@google.com> > >> > Cc: linux-mm@kvack.org > >> > Signed-off-by: Kees Cook <keescook@chromium.org> > >> > >> Thanks for your patch, which is now commit 63caa04ec60583b1 ("slab: > >> Remove __malloc attribute from realloc functions") in next-20220927. > >> > >> Noreply@ellerman.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. Kees submitted a similar patch 20 minutes before: https://lore.kernel.org/all/20220929081642.1932200-1-keescook@chromium.org > --- 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 -- geert@linux-m68k.org 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 <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: Roman Gushchin <roman.gushchin@linux.dev> > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Cc: Marco Elver <elver@google.com> > Cc: linux-mm@kvack.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > 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 <42.hyeyoo@gmail.com>
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;
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@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: Roman Gushchin <roman.gushchin@linux.dev> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Marco Elver <elver@google.com> Cc: linux-mm@kvack.org Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/compiler_types.h | 13 +++++-------- include/linux/slab.h | 12 ++++++------ mm/slab_common.c | 4 ++-- 3 files changed, 13 insertions(+), 16 deletions(-)