| Message ID | d0060171a76ace31b26fef1f2713da209099fb99.1605046192.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v9,01/44] kasan: drop unnecessary GPL text from comment headers | expand |
On Tue, Nov 10, 2020 at 11:12 PM Andrey Konovalov <andreyknvl@google.com> wrote: > > Kernel allocator code accesses metadata for slab objects, that may lie > out-of-bounds of the object itself, or be accessed when an object is freed. > Such accesses trigger tag faults and lead to false-positive reports with > hardware tag-based KASAN. > > Software KASAN modes disable instrumentation for allocator code via > KASAN_SANITIZE Makefile macro, and rely on kasan_enable/disable_current() > annotations which are used to ignore KASAN reports. > > With hardware tag-based KASAN neither of those options are available, as > it doesn't use compiler instrumetation, no tag faults are ignored, and MTE > is disabled after the first one. > > Instead, reset tags when accessing metadata (currently only for SLUB). > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > Acked-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> > --- > Change-Id: I39f3c4d4f29299d4fbbda039bedf230db1c746fb > --- > mm/page_alloc.c | 4 +++- > mm/page_poison.c | 2 +- > mm/slub.c | 29 ++++++++++++++++------------- > 3 files changed, 20 insertions(+), 15 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 24b45261e2bd..f1648aee8d88 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1195,8 +1195,10 @@ static void kernel_init_free_pages(struct page *page, int numpages) > > /* s390's use of memset() could override KASAN redzones. */ > kasan_disable_current(); > - for (i = 0; i < numpages; i++) > + for (i = 0; i < numpages; i++) { > + page_kasan_tag_reset(page + i); > clear_highpage(page + i); > + } > kasan_enable_current(); > } > > diff --git a/mm/page_poison.c b/mm/page_poison.c > index ae0482cded87..e6c994af7518 100644 > --- a/mm/page_poison.c > +++ b/mm/page_poison.c > @@ -53,7 +53,7 @@ static void poison_page(struct page *page) > > /* KASAN still think the page is in-use, so skip it. */ > kasan_disable_current(); > - memset(addr, PAGE_POISON, PAGE_SIZE); > + memset(kasan_reset_tag(addr), PAGE_POISON, PAGE_SIZE); > kasan_enable_current(); > kunmap_atomic(addr); > } > diff --git a/mm/slub.c b/mm/slub.c > index b30be2385d1c..df2fd5b57df1 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -249,7 +249,7 @@ static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr, > { > #ifdef CONFIG_SLAB_FREELIST_HARDENED > /* > - * When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. > + * When CONFIG_KASAN_SW/HW_TAGS is enabled, ptr_addr might be tagged. > * Normally, this doesn't cause any issues, as both set_freepointer() > * and get_freepointer() are called with a pointer with the same tag. > * However, there are some issues with CONFIG_SLUB_DEBUG code. For > @@ -275,6 +275,7 @@ static inline void *freelist_dereference(const struct kmem_cache *s, > > static inline void *get_freepointer(struct kmem_cache *s, void *object) > { > + object = kasan_reset_tag(object); > return freelist_dereference(s, object + s->offset); > } > > @@ -304,6 +305,7 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) > BUG_ON(object == fp); /* naive detection of double free or corruption */ > #endif > > + freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr); > *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr); > } > > @@ -538,8 +540,8 @@ static void print_section(char *level, char *text, u8 *addr, > unsigned int length) > { > metadata_access_enable(); > - print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr, > - length, 1); > + print_hex_dump(level, kasan_reset_tag(text), DUMP_PREFIX_ADDRESS, > + 16, 1, addr, length, 1); > metadata_access_disable(); > } > > @@ -570,7 +572,7 @@ static struct track *get_track(struct kmem_cache *s, void *object, > > p = object + get_info_end(s); > > - return p + alloc; > + return kasan_reset_tag(p + alloc); > } > > static void set_track(struct kmem_cache *s, void *object, > @@ -583,7 +585,8 @@ static void set_track(struct kmem_cache *s, void *object, > unsigned int nr_entries; > > metadata_access_enable(); > - nr_entries = stack_trace_save(p->addrs, TRACK_ADDRS_COUNT, 3); > + nr_entries = stack_trace_save(kasan_reset_tag(p->addrs), > + TRACK_ADDRS_COUNT, 3); > metadata_access_disable(); > > if (nr_entries < TRACK_ADDRS_COUNT) > @@ -747,7 +750,7 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, > > static void init_object(struct kmem_cache *s, void *object, u8 val) > { > - u8 *p = object; > + u8 *p = kasan_reset_tag(object); > > if (s->flags & SLAB_RED_ZONE) > memset(p - s->red_left_pad, val, s->red_left_pad); > @@ -777,7 +780,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, > u8 *addr = page_address(page); > > metadata_access_enable(); > - fault = memchr_inv(start, value, bytes); > + fault = memchr_inv(kasan_reset_tag(start), value, bytes); > metadata_access_disable(); > if (!fault) > return 1; > @@ -873,7 +876,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page) > > pad = end - remainder; > metadata_access_enable(); > - fault = memchr_inv(pad, POISON_INUSE, remainder); > + fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder); > metadata_access_disable(); > if (!fault) > return 1; > @@ -1118,7 +1121,7 @@ void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr) > return; > > metadata_access_enable(); > - memset(addr, POISON_INUSE, page_size(page)); > + memset(kasan_reset_tag(addr), POISON_INUSE, page_size(page)); > metadata_access_disable(); > } > > @@ -1566,10 +1569,10 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s, > * Clear the object and the metadata, but don't touch > * the redzone. > */ > - memset(object, 0, s->object_size); > + memset(kasan_reset_tag(object), 0, s->object_size); > rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad > : 0; > - memset((char *)object + s->inuse, 0, > + memset((char *)kasan_reset_tag(object) + s->inuse, 0, > s->size - s->inuse - rsize); > > } > @@ -2883,10 +2886,10 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, > stat(s, ALLOC_FASTPATH); > } > > - maybe_wipe_obj_freeptr(s, object); > + maybe_wipe_obj_freeptr(s, kasan_reset_tag(object)); > > if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) > - memset(object, 0, s->object_size); > + memset(kasan_reset_tag(object), 0, s->object_size); > > slab_post_alloc_hook(s, objcg, gfpflags, 1, &object); > > -- > 2.29.2.222.g5d2a92d10f8-goog >
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 24b45261e2bd..f1648aee8d88 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1195,8 +1195,10 @@ static void kernel_init_free_pages(struct page *page, int numpages) /* s390's use of memset() could override KASAN redzones. */ kasan_disable_current(); - for (i = 0; i < numpages; i++) + for (i = 0; i < numpages; i++) { + page_kasan_tag_reset(page + i); clear_highpage(page + i); + } kasan_enable_current(); } diff --git a/mm/page_poison.c b/mm/page_poison.c index ae0482cded87..e6c994af7518 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -53,7 +53,7 @@ static void poison_page(struct page *page) /* KASAN still think the page is in-use, so skip it. */ kasan_disable_current(); - memset(addr, PAGE_POISON, PAGE_SIZE); + memset(kasan_reset_tag(addr), PAGE_POISON, PAGE_SIZE); kasan_enable_current(); kunmap_atomic(addr); } diff --git a/mm/slub.c b/mm/slub.c index b30be2385d1c..df2fd5b57df1 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -249,7 +249,7 @@ static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr, { #ifdef CONFIG_SLAB_FREELIST_HARDENED /* - * When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. + * When CONFIG_KASAN_SW/HW_TAGS is enabled, ptr_addr might be tagged. * Normally, this doesn't cause any issues, as both set_freepointer() * and get_freepointer() are called with a pointer with the same tag. * However, there are some issues with CONFIG_SLUB_DEBUG code. For @@ -275,6 +275,7 @@ static inline void *freelist_dereference(const struct kmem_cache *s, static inline void *get_freepointer(struct kmem_cache *s, void *object) { + object = kasan_reset_tag(object); return freelist_dereference(s, object + s->offset); } @@ -304,6 +305,7 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) BUG_ON(object == fp); /* naive detection of double free or corruption */ #endif + freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr); *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr); } @@ -538,8 +540,8 @@ static void print_section(char *level, char *text, u8 *addr, unsigned int length) { metadata_access_enable(); - print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr, - length, 1); + print_hex_dump(level, kasan_reset_tag(text), DUMP_PREFIX_ADDRESS, + 16, 1, addr, length, 1); metadata_access_disable(); } @@ -570,7 +572,7 @@ static struct track *get_track(struct kmem_cache *s, void *object, p = object + get_info_end(s); - return p + alloc; + return kasan_reset_tag(p + alloc); } static void set_track(struct kmem_cache *s, void *object, @@ -583,7 +585,8 @@ static void set_track(struct kmem_cache *s, void *object, unsigned int nr_entries; metadata_access_enable(); - nr_entries = stack_trace_save(p->addrs, TRACK_ADDRS_COUNT, 3); + nr_entries = stack_trace_save(kasan_reset_tag(p->addrs), + TRACK_ADDRS_COUNT, 3); metadata_access_disable(); if (nr_entries < TRACK_ADDRS_COUNT) @@ -747,7 +750,7 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, static void init_object(struct kmem_cache *s, void *object, u8 val) { - u8 *p = object; + u8 *p = kasan_reset_tag(object); if (s->flags & SLAB_RED_ZONE) memset(p - s->red_left_pad, val, s->red_left_pad); @@ -777,7 +780,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, u8 *addr = page_address(page); metadata_access_enable(); - fault = memchr_inv(start, value, bytes); + fault = memchr_inv(kasan_reset_tag(start), value, bytes); metadata_access_disable(); if (!fault) return 1; @@ -873,7 +876,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page) pad = end - remainder; metadata_access_enable(); - fault = memchr_inv(pad, POISON_INUSE, remainder); + fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder); metadata_access_disable(); if (!fault) return 1; @@ -1118,7 +1121,7 @@ void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr) return; metadata_access_enable(); - memset(addr, POISON_INUSE, page_size(page)); + memset(kasan_reset_tag(addr), POISON_INUSE, page_size(page)); metadata_access_disable(); } @@ -1566,10 +1569,10 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s, * Clear the object and the metadata, but don't touch * the redzone. */ - memset(object, 0, s->object_size); + memset(kasan_reset_tag(object), 0, s->object_size); rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0; - memset((char *)object + s->inuse, 0, + memset((char *)kasan_reset_tag(object) + s->inuse, 0, s->size - s->inuse - rsize); } @@ -2883,10 +2886,10 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, stat(s, ALLOC_FASTPATH); } - maybe_wipe_obj_freeptr(s, object); + maybe_wipe_obj_freeptr(s, kasan_reset_tag(object)); if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) - memset(object, 0, s->object_size); + memset(kasan_reset_tag(object), 0, s->object_size); slab_post_alloc_hook(s, objcg, gfpflags, 1, &object);