On Fri, May 22, 2020 at 4:01 AM Walter Wu <walter-zh.wu@xxxxxxxxxxxx> wrote: > > Move free track from kasan_alloc_meta to kasan_free_meta in order > to make struct kasan_alloc_meta and kasan_free_meta size are both > 16 bytes. It is a good size because it is the minimal redzone size > and a good number of alignment. > > For free track, we make some modifications as shown below: > 1) Remove the free_track from struct kasan_alloc_meta. > 2) Add the free_track into struct kasan_free_meta. > 3) Add a macro KASAN_KMALLOC_FREETRACK in order to check whether > it can print free stack in KASAN report. > > [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 Reviewed-and-tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> > Suggested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Co-developed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Alexander Potapenko <glider@xxxxxxxxxx> > --- > mm/kasan/common.c | 22 ++-------------------- > mm/kasan/generic.c | 22 ++++++++++++++++++++++ > mm/kasan/generic_report.c | 1 + > mm/kasan/kasan.h | 13 +++++++++++-- > mm/kasan/quarantine.c | 1 + > mm/kasan/report.c | 26 ++++---------------------- > mm/kasan/tags.c | 37 +++++++++++++++++++++++++++++++++++++ > 7 files changed, 78 insertions(+), 44 deletions(-) > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 8bc618289bb1..47b53912f322 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -51,7 +51,7 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags) > return stack_depot_save(entries, nr_entries, flags); > } > > -static inline void set_track(struct kasan_track *track, gfp_t flags) > +void kasan_set_track(struct kasan_track *track, gfp_t flags) > { > track->pid = current->pid; > track->stack = kasan_save_stack(flags); > @@ -299,24 +299,6 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache, > return (void *)object + cache->kasan_info.free_meta_offset; > } > > - > -static void kasan_set_free_info(struct kmem_cache *cache, > - void *object, u8 tag) > -{ > - struct kasan_alloc_meta *alloc_meta; > - u8 idx = 0; > - > - alloc_meta = get_alloc_info(cache, object); > - > -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY > - idx = alloc_meta->free_track_idx; > - alloc_meta->free_pointer_tag[idx] = tag; > - alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS; > -#endif > - > - set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); > -} > - > void kasan_poison_slab(struct page *page) > { > unsigned long i; > @@ -492,7 +474,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, > KASAN_KMALLOC_REDZONE); > > if (cache->flags & SLAB_KASAN) > - set_track(&get_alloc_info(cache, object)->alloc_track, flags); > + kasan_set_track(&get_alloc_info(cache, object)->alloc_track, flags); > > return set_tag(object, tag); > } > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > index 8acf48882ba2..4b3cbad7431b 100644 > --- a/mm/kasan/generic.c > +++ b/mm/kasan/generic.c > @@ -346,3 +346,25 @@ void kasan_record_aux_stack(void *addr) > alloc_info->aux_stack[1] = alloc_info->aux_stack[0]; > alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT); > } > + > +void kasan_set_free_info(struct kmem_cache *cache, > + void *object, u8 tag) > +{ > + struct kasan_free_meta *free_meta; > + > + free_meta = get_free_info(cache, object); > + kasan_set_track(&free_meta->free_track, GFP_NOWAIT); > + > + /* > + * the object was freed and has free track set > + */ > + *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK; > +} > + > +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, > + void *object, u8 tag) > +{ > + if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK) > + return NULL; > + return &get_free_info(cache, object)->free_track; > +} > diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c > index e200acb2d292..a38c7a9e192a 100644 > --- a/mm/kasan/generic_report.c > +++ b/mm/kasan/generic_report.c > @@ -80,6 +80,7 @@ static const char *get_shadow_bug_type(struct kasan_access_info *info) > break; > case KASAN_FREE_PAGE: > case KASAN_KMALLOC_FREE: > + case KASAN_KMALLOC_FREETRACK: > bug_type = "use-after-free"; > break; > case KASAN_ALLOCA_LEFT: > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index a7391bc83070..ef655a1c6e15 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -17,15 +17,17 @@ > #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */ > #define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */ > #define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */ > +#define KASAN_KMALLOC_FREETRACK 0xFA /* object was freed and has free track set */ > #else > #define KASAN_FREE_PAGE KASAN_TAG_INVALID > #define KASAN_PAGE_REDZONE KASAN_TAG_INVALID > #define KASAN_KMALLOC_REDZONE KASAN_TAG_INVALID > #define KASAN_KMALLOC_FREE KASAN_TAG_INVALID > +#define KASAN_KMALLOC_FREETRACK KASAN_TAG_INVALID > #endif > > -#define KASAN_GLOBAL_REDZONE 0xFA /* redzone for global variable */ > -#define KASAN_VMALLOC_INVALID 0xF9 /* unallocated space in vmapped page */ > +#define KASAN_GLOBAL_REDZONE 0xF9 /* redzone for global variable */ > +#define KASAN_VMALLOC_INVALID 0xF8 /* unallocated space in vmapped page */ > > /* > * Stack redzone shadow values > @@ -127,6 +129,9 @@ struct kasan_free_meta { > * Otherwise it might be used for the allocator freelist. > */ > struct qlist_node quarantine_link; > +#ifdef CONFIG_KASAN_GENERIC > + struct kasan_track free_track; > +#endif > }; > > struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, > @@ -168,6 +173,10 @@ void kasan_report_invalid_free(void *object, unsigned long ip); > struct page *kasan_addr_to_page(const void *addr); > > depot_stack_handle_t kasan_save_stack(gfp_t flags); > +void kasan_set_track(struct kasan_track *track, gfp_t flags); > +void kasan_set_free_info(struct kmem_cache *cache, void *object, u8 tag); > +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, > + void *object, u8 tag); > > #if defined(CONFIG_KASAN_GENERIC) && \ > (defined(CONFIG_SLAB) || defined(CONFIG_SLUB)) > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c > index 978bc4a3eb51..4c5375810449 100644 > --- a/mm/kasan/quarantine.c > +++ b/mm/kasan/quarantine.c > @@ -145,6 +145,7 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache) > if (IS_ENABLED(CONFIG_SLAB)) > local_irq_save(flags); > > + *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREE; > ___cache_free(cache, object, _THIS_IP_); > > if (IS_ENABLED(CONFIG_SLAB)) > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > index 2421a4bd9227..fed3c8fdfd25 100644 > --- a/mm/kasan/report.c > +++ b/mm/kasan/report.c > @@ -164,26 +164,6 @@ static void describe_object_addr(struct kmem_cache *cache, void *object, > (void *)(object_addr + cache->object_size)); > } > > -static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, > - void *object, u8 tag) > -{ > - struct kasan_alloc_meta *alloc_meta; > - int i = 0; > - > - alloc_meta = get_alloc_info(cache, object); > - > -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY > - for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { > - if (alloc_meta->free_pointer_tag[i] == tag) > - break; > - } > - if (i == KASAN_NR_FREE_STACKS) > - i = alloc_meta->free_track_idx; > -#endif > - > - return &alloc_meta->free_track[i]; > -} > - > static void describe_object(struct kmem_cache *cache, void *object, > const void *addr, u8 tag) > { > @@ -195,8 +175,10 @@ static void describe_object(struct kmem_cache *cache, void *object, > print_track(&alloc_info->alloc_track, "Allocated"); > pr_err("\n"); > free_track = kasan_get_free_track(cache, object, tag); > - print_track(free_track, "Freed"); > - pr_err("\n"); > + if (free_track) { > + print_track(free_track, "Freed"); > + pr_err("\n"); > + } > > #ifdef CONFIG_KASAN_GENERIC > if (alloc_info->aux_stack[0]) { > diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c > index 25b7734e7013..201dee5d6ae0 100644 > --- a/mm/kasan/tags.c > +++ b/mm/kasan/tags.c > @@ -162,3 +162,40 @@ void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size) > kasan_poison_shadow((void *)addr, size, tag); > } > EXPORT_SYMBOL(__hwasan_tag_memory); > + > +void kasan_set_free_info(struct kmem_cache *cache, > + void *object, u8 tag) > +{ > + struct kasan_alloc_meta *alloc_meta; > + u8 idx = 0; > + > + alloc_meta = get_alloc_info(cache, object); > + > +#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY > + idx = alloc_meta->free_track_idx; > + alloc_meta->free_pointer_tag[idx] = tag; > + alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS; > +#endif > + > + kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); > +} > + > +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, > + void *object, u8 tag) > +{ > + struct kasan_alloc_meta *alloc_meta; > + int i = 0; > + > + alloc_meta = get_alloc_info(cache, object); > + > +#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY > + for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { > + if (alloc_meta->free_pointer_tag[i] == tag) > + break; > + } > + if (i == KASAN_NR_FREE_STACKS) > + i = alloc_meta->free_track_idx; > +#endif > + > + return &alloc_meta->free_track[i]; > +} > -- > 2.18.0 > > -- > 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@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20200522020127.23335-1-walter-zh.wu%40mediatek.com.
