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dkim=pass header.d=gmail.com header.s=20210112 header.b="kKI9Y/dP"; spf=pass (imf30.hostedemail.com: domain of andreyknvl@gmail.com designates 209.85.160.173 as permitted sender) smtp.mailfrom=andreyknvl@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam06 X-Stat-Signature: 6spxiqt7rgxjxiytjdupnzzs97mydcci X-Rspamd-Queue-Id: 8254A800B0 X-HE-Tag: 1662851490-207436 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Sep 7, 2022 at 9:10 AM Feng Tang wrote: > > kzalloc/kmalloc will round up the request size to a fixed size > (mostly power of 2), so the allocated memory could be more than > requested. Currently kzalloc family APIs will zero all the > allocated memory. > > To detect out-of-bound usage of the extra allocated memory, only > zero the requested part, so that sanity check could be added to > the extra space later. > > For kzalloc users who will call ksize() later and utilize this > extra space, please be aware that the space is not zeroed any > more. > > Signed-off-by: Feng Tang > --- > mm/slab.c | 6 +++--- > mm/slab.h | 9 +++++++-- > mm/slub.c | 6 +++--- > 3 files changed, 13 insertions(+), 8 deletions(-) > > diff --git a/mm/slab.c b/mm/slab.c > index a5486ff8362a..73ecaa7066e1 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -3253,7 +3253,7 @@ slab_alloc_node(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags, > init = slab_want_init_on_alloc(flags, cachep); > > out: > - slab_post_alloc_hook(cachep, objcg, flags, 1, &objp, init); > + slab_post_alloc_hook(cachep, objcg, flags, 1, &objp, init, 0); > return objp; > } > > @@ -3506,13 +3506,13 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, > * Done outside of the IRQ disabled section. > */ > slab_post_alloc_hook(s, objcg, flags, size, p, > - slab_want_init_on_alloc(flags, s)); > + slab_want_init_on_alloc(flags, s), 0); > /* FIXME: Trace call missing. Christoph would like a bulk variant */ > return size; > error: > local_irq_enable(); > cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_); > - slab_post_alloc_hook(s, objcg, flags, i, p, false); > + slab_post_alloc_hook(s, objcg, flags, i, p, false, 0); > kmem_cache_free_bulk(s, i, p); > return 0; > } > diff --git a/mm/slab.h b/mm/slab.h > index d0ef9dd44b71..20f9e2a9814f 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -730,12 +730,17 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, > > static inline void slab_post_alloc_hook(struct kmem_cache *s, > struct obj_cgroup *objcg, gfp_t flags, > - size_t size, void **p, bool init) > + size_t size, void **p, bool init, > + unsigned int orig_size) > { > size_t i; > > flags &= gfp_allowed_mask; > > + /* If original request size(kmalloc) is not set, use object_size */ > + if (!orig_size) > + orig_size = s->object_size; > + > /* > * As memory initialization might be integrated into KASAN, > * kasan_slab_alloc and initialization memset must be > @@ -746,7 +751,7 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, > for (i = 0; i < size; i++) { > p[i] = kasan_slab_alloc(s, p[i], flags, init); > if (p[i] && init && !kasan_has_integrated_init()) > - memset(p[i], 0, s->object_size); > + memset(p[i], 0, orig_size); Arguably, with slab_want_init_on_alloc(), all allocated memory should be zeroed to prevent possibility of info-leaks, even unused paddings. Perhaps, Alexander can give his opinion here. Thanks! > kmemleak_alloc_recursive(p[i], s->object_size, 1, > s->flags, flags); > } > diff --git a/mm/slub.c b/mm/slub.c > index effd994438e6..f523601d3fcf 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3376,7 +3376,7 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, struct list_l > init = slab_want_init_on_alloc(gfpflags, s); > > out: > - slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init); > + slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init, orig_size); > > return object; > } > @@ -3833,11 +3833,11 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, > * Done outside of the IRQ disabled fastpath loop. > */ > slab_post_alloc_hook(s, objcg, flags, size, p, > - slab_want_init_on_alloc(flags, s)); > + slab_want_init_on_alloc(flags, s), 0); > return i; > error: > slub_put_cpu_ptr(s->cpu_slab); > - slab_post_alloc_hook(s, objcg, flags, i, p, false); > + slab_post_alloc_hook(s, objcg, flags, i, p, false, 0); > kmem_cache_free_bulk(s, i, p); > return 0; > } > -- > 2.34.1 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20220907071023.3838692-3-feng.tang%40intel.com.