| Message ID | 20230915105933.495735-6-matteorizzo@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Prevent cross-cache attacks in the SLUB allocator | expand |
On Fri, Sep 15, 2023 at 10:59:24AM +0000, Matteo Rizzo wrote: > From: Jann Horn <jannh@google.com> > > This is refactoring in preparation for SLAB_VIRTUAL. Extract this code > to separate functions so that it's not duplicated in the code that > allocates and frees page with SLAB_VIRTUAL enabled. > > Signed-off-by: Jann Horn <jannh@google.com> > Co-developed-by: Matteo Rizzo <matteorizzo@google.com> > Signed-off-by: Matteo Rizzo <matteorizzo@google.com> > --- > mm/slub.c | 32 ++++++++++++++++++++++---------- > 1 file changed, 22 insertions(+), 10 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index ad33d9e1601d..9b87afade125 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1849,6 +1849,26 @@ static void *setup_object(struct kmem_cache *s, void *object) > /* > * Slab allocation and freeing > */ > + > +static void folio_set_slab(struct folio *folio, struct slab *slab) > +{ > + __folio_set_slab(folio); > + /* Make the flag visible before any changes to folio->mapping */ > + smp_wmb(); > + > + if (folio_is_pfmemalloc(folio)) > + slab_set_pfmemalloc(slab); > +} > + > +static void folio_clear_slab(struct folio *folio, struct slab *slab) > +{ > + __slab_clear_pfmemalloc(slab); > + folio->mapping = NULL; > + /* Make the mapping reset visible before clearing the flag */ > + smp_wmb(); > + __folio_clear_slab(folio); > +} Perhaps these should be explicitly marked as inlines? > + > static inline struct slab *alloc_slab_page(gfp_t flags, int node, > struct kmem_cache_order_objects oo) > { > @@ -1865,11 +1885,7 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node, > return NULL; > > slab = folio_slab(folio); > - __folio_set_slab(folio); > - /* Make the flag visible before any changes to folio->mapping */ > - smp_wmb(); > - if (folio_is_pfmemalloc(folio)) > - slab_set_pfmemalloc(slab); > + folio_set_slab(folio, slab); > > return slab; > } > @@ -2067,11 +2083,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab) > int order = folio_order(folio); > int pages = 1 << order; > > - __slab_clear_pfmemalloc(slab); > - folio->mapping = NULL; > - /* Make the mapping reset visible before clearing the flag */ > - smp_wmb(); > - __folio_clear_slab(folio); > + folio_clear_slab(folio, slab); > mm_account_reclaimed_pages(pages); > unaccount_slab(slab, order, s); > __free_pages(&folio->page, order); > -- > 2.42.0.459.ge4e396fd5e-goog Otherwise this is a straight function extraction. Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/mm/slub.c b/mm/slub.c index ad33d9e1601d..9b87afade125 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1849,6 +1849,26 @@ static void *setup_object(struct kmem_cache *s, void *object) /* * Slab allocation and freeing */ + +static void folio_set_slab(struct folio *folio, struct slab *slab) +{ + __folio_set_slab(folio); + /* Make the flag visible before any changes to folio->mapping */ + smp_wmb(); + + if (folio_is_pfmemalloc(folio)) + slab_set_pfmemalloc(slab); +} + +static void folio_clear_slab(struct folio *folio, struct slab *slab) +{ + __slab_clear_pfmemalloc(slab); + folio->mapping = NULL; + /* Make the mapping reset visible before clearing the flag */ + smp_wmb(); + __folio_clear_slab(folio); +} + static inline struct slab *alloc_slab_page(gfp_t flags, int node, struct kmem_cache_order_objects oo) { @@ -1865,11 +1885,7 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node, return NULL; slab = folio_slab(folio); - __folio_set_slab(folio); - /* Make the flag visible before any changes to folio->mapping */ - smp_wmb(); - if (folio_is_pfmemalloc(folio)) - slab_set_pfmemalloc(slab); + folio_set_slab(folio, slab); return slab; } @@ -2067,11 +2083,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab) int order = folio_order(folio); int pages = 1 << order; - __slab_clear_pfmemalloc(slab); - folio->mapping = NULL; - /* Make the mapping reset visible before clearing the flag */ - smp_wmb(); - __folio_clear_slab(folio); + folio_clear_slab(folio, slab); mm_account_reclaimed_pages(pages); unaccount_slab(slab, order, s); __free_pages(&folio->page, order);