From 145cd60fb481328faafba76842aa0fd242e2b163 Mon Sep 17 00:00:00 2001 From: Alexander Potapenko Date: Tue, 24 Nov 2020 16:38:44 +1100 Subject: mm, kfence: insert KFENCE hooks for SLUB Inserts KFENCE hooks into the SLUB allocator. To pass the originally requested size to KFENCE, add an argument 'orig_size' to slab_alloc*(). The additional argument is required to preserve the requested original size for kmalloc() allocations, which uses size classes (e.g. an allocation of 272 bytes will return an object of size 512). Therefore, kmem_cache::size does not represent the kmalloc-caller's requested size, and we must introduce the argument 'orig_size' to propagate the originally requested size to KFENCE. Without the originally requested size, we would not be able to detect out-of-bounds accesses for objects placed at the end of a KFENCE object page if that object is not equal to the kmalloc-size class it was bucketed into. When KFENCE is disabled, there is no additional overhead, since slab_alloc*() functions are __always_inline. Link: https://lkml.kernel.org/r/20201103175841.3495947-6-elver@google.com Signed-off-by: Marco Elver Signed-off-by: Alexander Potapenko Reviewed-by: Dmitry Vyukov Reviewed-by: Jann Horn Co-developed-by: Marco Elver Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christopher Lameter Cc: Dave Hansen Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Hillf Danton Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joern Engel Cc: Jonathan Corbet Cc: Joonsoo Kim Cc: Kees Cook Cc: Mark Rutland Cc: Paul E. McKenney Cc: Pekka Enberg Cc: Peter Zijlstra Cc: SeongJae Park Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Stephen Rothwell --- mm/kfence/core.c | 2 ++ mm/slub.c | 60 +++++++++++++++++++++++++++++++++++++++++++------------- 2 files changed, 48 insertions(+), 14 deletions(-) (limited to 'mm') diff --git a/mm/kfence/core.c b/mm/kfence/core.c index e602d44c1e7f..933b197b8634 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -313,6 +313,8 @@ static void *kfence_guarded_alloc(struct kmem_cache *cache, size_t size, gfp_t g /* Set required struct page fields. */ page = virt_to_page(meta->addr); page->slab_cache = cache; + if (IS_ENABLED(CONFIG_SLUB)) + page->objects = 1; if (IS_ENABLED(CONFIG_SLAB)) page->s_mem = addr; diff --git a/mm/slub.c b/mm/slub.c index be7151fe6cc0..cc1173928e6b 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -1553,6 +1554,11 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s, void *old_tail = *tail ? *tail : *head; int rsize; + if (is_kfence_address(next)) { + slab_free_hook(s, next); + return true; + } + /* Head and tail of the reconstructed freelist */ *head = NULL; *tail = NULL; @@ -2803,7 +2809,7 @@ static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s, * Otherwise we can simply pick the next object from the lockless free list. */ static __always_inline void *slab_alloc_node(struct kmem_cache *s, - gfp_t gfpflags, int node, unsigned long addr) + gfp_t gfpflags, int node, unsigned long addr, size_t orig_size) { void *object; struct kmem_cache_cpu *c; @@ -2814,6 +2820,11 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, s = slab_pre_alloc_hook(s, &objcg, 1, gfpflags); if (!s) return NULL; + + object = kfence_alloc(s, orig_size, gfpflags); + if (unlikely(object)) + goto out; + redo: /* * Must read kmem_cache cpu data via this cpu ptr. Preemption is @@ -2886,20 +2897,21 @@ redo: if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) memset(object, 0, s->object_size); +out: slab_post_alloc_hook(s, objcg, gfpflags, 1, &object); return object; } static __always_inline void *slab_alloc(struct kmem_cache *s, - gfp_t gfpflags, unsigned long addr) + gfp_t gfpflags, unsigned long addr, size_t orig_size) { - return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr); + return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr, orig_size); } void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags) { - void *ret = slab_alloc(s, gfpflags, _RET_IP_); + void *ret = slab_alloc(s, gfpflags, _RET_IP_, s->object_size); trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size, s->size, gfpflags); @@ -2911,7 +2923,7 @@ EXPORT_SYMBOL(kmem_cache_alloc); #ifdef CONFIG_TRACING void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) { - void *ret = slab_alloc(s, gfpflags, _RET_IP_); + void *ret = slab_alloc(s, gfpflags, _RET_IP_, size); trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags); ret = kasan_kmalloc(s, ret, size, gfpflags); return ret; @@ -2922,7 +2934,7 @@ EXPORT_SYMBOL(kmem_cache_alloc_trace); #ifdef CONFIG_NUMA void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node) { - void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_); + void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_, s->object_size); trace_kmem_cache_alloc_node(_RET_IP_, ret, s->object_size, s->size, gfpflags, node); @@ -2936,7 +2948,7 @@ void *kmem_cache_alloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, int node, size_t size) { - void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_); + void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_, size); trace_kmalloc_node(_RET_IP_, ret, size, s->size, gfpflags, node); @@ -2970,6 +2982,9 @@ static void __slab_free(struct kmem_cache *s, struct page *page, stat(s, FREE_SLOWPATH); + if (kfence_free(head)) + return; + if (kmem_cache_debug(s) && !free_debug_processing(s, page, head, tail, cnt, addr)) return; @@ -3214,6 +3229,13 @@ int build_detached_freelist(struct kmem_cache *s, size_t size, df->s = cache_from_obj(s, object); /* Support for memcg */ } + if (is_kfence_address(object)) { + slab_free_hook(df->s, object); + __kfence_free(object); + p[size] = NULL; /* mark object processed */ + return size; + } + /* Start new detached freelist */ df->page = page; set_freepointer(df->s, object, NULL); @@ -3289,8 +3311,14 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, c = this_cpu_ptr(s->cpu_slab); for (i = 0; i < size; i++) { - void *object = c->freelist; + void *object = kfence_alloc(s, s->object_size, flags); + if (unlikely(object)) { + p[i] = object; + continue; + } + + object = c->freelist; if (unlikely(!object)) { /* * We may have removed an object from c->freelist using @@ -3961,7 +3989,7 @@ void *__kmalloc(size_t size, gfp_t flags) if (unlikely(ZERO_OR_NULL_PTR(s))) return s; - ret = slab_alloc(s, flags, _RET_IP_); + ret = slab_alloc(s, flags, _RET_IP_, size); trace_kmalloc(_RET_IP_, ret, size, s->size, flags); @@ -4009,7 +4037,7 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node) if (unlikely(ZERO_OR_NULL_PTR(s))) return s; - ret = slab_alloc_node(s, flags, node, _RET_IP_); + ret = slab_alloc_node(s, flags, node, _RET_IP_, size); trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node); @@ -4035,6 +4063,7 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, struct kmem_cache *s; unsigned int offset; size_t object_size; + bool is_kfence = is_kfence_address(ptr); ptr = kasan_reset_tag(ptr); @@ -4047,10 +4076,13 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, to_user, 0, n); /* Find offset within object. */ - offset = (ptr - page_address(page)) % s->size; + if (is_kfence) + offset = ptr - kfence_object_start(ptr); + else + offset = (ptr - page_address(page)) % s->size; /* Adjust for redzone and reject if within the redzone. */ - if (kmem_cache_debug_flags(s, SLAB_RED_ZONE)) { + if (!is_kfence && kmem_cache_debug_flags(s, SLAB_RED_ZONE)) { if (offset < s->red_left_pad) usercopy_abort("SLUB object in left red zone", s->name, to_user, offset, n); @@ -4459,7 +4491,7 @@ void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller) if (unlikely(ZERO_OR_NULL_PTR(s))) return s; - ret = slab_alloc(s, gfpflags, caller); + ret = slab_alloc(s, gfpflags, caller, size); /* Honor the call site pointer we received. */ trace_kmalloc(caller, ret, size, s->size, gfpflags); @@ -4490,7 +4522,7 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags, if (unlikely(ZERO_OR_NULL_PTR(s))) return s; - ret = slab_alloc_node(s, gfpflags, node, caller); + ret = slab_alloc_node(s, gfpflags, node, caller, size); /* Honor the call site pointer we received. */ trace_kmalloc_node(caller, ret, size, s->size, gfpflags, node); -- cgit v1.2.1